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The comprehensive approach in SCERT Kerala Syllabus 10th Standard Physics Textbook Solutions and Class 10 Physics Chapter 7 Mechanical Advantage in Action Notes Questions and Answers English Medium ensure conceptual clarity.

SSLC Physics Chapter 7 Notes Questions and Answers Pdf Mechanical Advantage in Action

SCERT Class 10 Physics Chapter 7 Mechanical Advantage in Action Notes Pdf

SSLC Physics Chapter 7 Questions and Answers – Let’s Assess

Question 1.
Write down an example of a lever where the load arm and effort arm are equal. What is its mechanical advantage?
Answer:
Common balance
Mechanical advantage = 1

Question 2.
In which order of lever is the load arm longer than the effort arm? Write down an example. Which may be the possible mechanical advantage? Choose from the brackets.
(less than one/one/more than one)
Answer:
Third order of lever
Example: ice tongs
less than one

Question 3.
As shown in the figure, an object is suspended from one end of a meter scale. When 400 gwt is suspended from the midpoint of the other side, the scale is balanced. What is the mass of the object? What is the weight of the object?

Answer:
Load = x
Load arm = 50 cm
Effort = 400 gwt
Effort arm = 25 cm
\(\frac{\text { Load }}{\text { Effort }}\) = \(\frac{\text { Effort arm }}{\text { Load arm }}\)
\(\frac{x}{400}\) = \(\frac{25}{50}\)
x = 200 gwt
Mass of the object = 200 g
Weight of the object = 200 gwt

Question 4.
In which type of lever is the mechanical advantage always greater than one?
Answer:
Second order lever

Question 5.
Draw a schematic diagram of a second order lever. Mark the fulcrum, load, and effort. Explain why the mechanical advantage of this is neither one nor less than one.
Answer:

Mechanical advantage = \(\frac{\text { Effort arm }}{\text { Load arm }}\)
As the load comes in between the fulcrum and effort, the effort arm will always be greater than the load arm. So the mechanical advantage of a second order lever is neither one nor less than one.

Question 6.
A log weighing 5000 kgwt is lifted through a height of 2 m onto a lorry using an inclined plane. A force of 2000 N was applied. What is the length of the inclined plane used to lift the log? What is the mechanical advantage in this situation? (Consider g = 10 m/s²)
Answer:
Mechanical advantage of an inclined plane, MA
= (L/E) = (l\h)
L = Load = 5000 kgwt = 5000 ×
10 N = 50000 N
E = Effort = 2000 N
Mechanical advantage = \(\frac{L}{E}\) = \(\frac{50000}{2000}\) = 25
l/h = 25
h = 2 m
Length of the inclined plane, = 2 × 25 = 50 m

Question 7.
How will you calculate the mechanical advantage of a screw? Describe an experiment to prove that a screw is an inclined plane.
Answer:
Mechanical advantage of a screw
=length of one thread /pitch Cut a paper in the shape of an inclined plane. Colour its slanting edge as in Fig.7.35(a)
Wrap this paper around a cylindrical pencil as in Fig.7.35(b).
We can see the coloured lines that appear as rings on the pencil look,like a screw.

Question 8.
A load of 1600 kgwt is suspended from an axle with a diameter of 6 cm. What should be the force applied in newton, to turn a 3 m long lever on one side of the axle, to lift this load? (Consider g = 10 m/s²)
Answer:
Mechanical advantage of axle and wheel = \(\frac{R}{r}\) = \(\frac{L}{E}\)
Diameter of the axle = 6 cm
Radius of the axle, r = 3 cm
Load = L = 1600 kgwt
= 1600 × 10 N
= 16000 N
\(\frac{L}{E}\) = \(\frac{R}{r}\)
\(\frac{16000}{E}\) = \(\frac{1}{2}\)
Effort, E = 160 N

Question 9.
Explain the necessity of gears in vehicles.
Answer:
While going uphill, large wheel is connected to the toothed wheel attached to the engine. When connected to a large toothed wheel, the speed of the vehicle decreases, but its efficiency to rotate increases.

To increase the speed of the vehicle, the toothed wheel attached to the engine must be connected to the small toothed wheel that helps to turn the tyre of the vehicle.

Question 10.
Match appropriately.

Lever	A	B	C
First order	Load is always more than the effort	Fulcrum comes in between effort and load	Mechanical advantage is always less than one
Second order	Load can be equal to, lesser or greater than the effort	Effort comes in between fulcrum and load	Mechanical advantage is always more than one
Third order	Load is always less than the effort	Load comes in between effort and fulcrum	Mechanical advantage is always equal to one or greater than one or lesser than one.

Answer:

Lever	A	B	C
First order	Load can be equal to, lesser or greater than the effort	Fulcrum comes in between effort and load	Mechanical advantage is equal to one or greater than one or lesser than one.
Second order	Load is always more than the effort	Load comes in between effort and fulcrum	Mechanical advantage is always more than one
Third order	Load is always less than the effort	Effort comes in between fulcrum and load	Mechanical advantage is always less than one

Physics Class 10 Chapter 7 Notes Kerala Syllabus Mechanical Advantage in Action

Question 1.
Observe the pictures given below. Name the simple machines shown in the pictures.


Answer:
Fig.7.1 (a) – Ramp as inclined plane
Fig.7.1 (b) – Spoon
Fig.7.1 (c) – Nail cutter
Fig.7.1 (d) – Bottle opener
Fig.7.1 (e) – Lever in the pump

Question 2.
How did these devices alleviate exertion?
Answer:
These devices reduce exertion by using simple machines (such as pumps, levers, and wedges) to change force or change its direction and thus helps to complete the task easily.

Question 3.
Observe the pictures. Analyse the situations in which a nail is pulled out.

a) In which situation [Fig. 7.2 (a), Fig. 7.2 (b)] was more force applied?
Answer:
In Fig. 7.2 (a)

b) Which device helped to increase the effect of the force we applied many folds?
Answer:
Nail puller

Question 4.
Observe the two ways of drawing water from a well.

a) In both the situations [Fig. 7.3(a), Fig. 7.3 (b)], is the force applied in the same direction?
Answer:
No, the force applied is not in the same direction in both situations.

b) In which direction is it more convenient to apply force?
Answer:
It more convenient to apply force in the downward direction as in situations in Fig. 7.3(b)

c) What is the benefit of using a pulley?
Answer:
Pulley helps to change the applied force in a more convenient direction, that is in the downward direction.

Question 5.
Analyse the situations in Fig. 7.2(a), Fig. 7.2(b) and Fig. 7.3(a), Fig. 7.3(b). Answer the questions given below.


a) In which situation did the effect of the force we applied increase many fold?
Answer:
In Fig. 7.2(b) and Fig. 7.3(b)

b) Which device increased the effect of the applied force many fold?
Answer:
Nail puller

c) Which device helped to change the direction of the applied force?
Answer:
Pulley

Advantages of using simple machines.

• Changes the magnitude of the effect of the force,
• Changes the direction of the applied force.

Simple machines are devices that change the magnitude of the effect offorce or the direction of the force or both.

Question 6.
How many types of simple machines are there? What are they?
Answer:
There are mainly six types of simple machines.
They are:

1. Lever
2. Pulley
3. Wheel and axle
4. Inclined plane
5. Screw
6. Wedge

Question 7.
When we squeeze a lemon using lemon squeezer,

a) What is the force we apply on the lemon squeezer?
(F₁/F₂)
Answer:
F₁

b) What is the force the lemon applies against the force we apply? (F₁/ F₂)
Answer:
F₂

When a lemon squeezer is used as a simple machine, the force we apply to squeeze the lemon is the effort. The force the lemon applies is the load.

The force we apply to a simple machine is the effort (E). The force the simple machine has to overcome is the load (L).

Question 8.
Identify the load and the effort while removing a nail using a nail puller [Fig. 7.2 (b)]. Note them down in your science diary.

Answer:
The force we apply to the nail puller is the effort (E).
The force the nail applies to the nail puller is the load (L).

Question 9.
Observe the picture of lifting a stone weighing 400 N, using a crowbar.

a) What is the weight lifted using the crowbar?
Ans:
400 N

b) What is the magnitude of force applied?
Answer:
100 N

c) How many times did the effect of the force applied increase?
Answer:
Four times

d) What is the advantage of using a crowbar?
Answer:
The effect of the force applied increased four times. That is the effect of the effort is increased by four times.

Question 10.
If a simple machine can lift a load four times the effort,
a) What is the ratio between the load and the effort?
Answer:
The ratio between the load and the effort is four.

b) How much is the mechanical advantage in the above case?
Answer:
mechanical advantage in the above case is four.

c) How many times did the effect of the force applied increase?
Answer:
Here the effect of the effort is increased by four times.

Mechanical advantage (MA) is the ratio of the load to the effort. It is a number indicating how many times of the load is the effort. Mechanical advantage is only a ratio. It has no unit Mechanical advantage, MA = \(\frac{\text { Load }}{\text { Effort }}\)

Question 11.
A force of 40 N was applied on a nail puller to pull a nail. If the mechanical advantage of the nail puller was three, what would be the load applied by the nail?
Answer:
Mechanical advantage = \(\frac{\text { Load }}{\text { Effort }}\)
Mechanical advantage = 3
Effort = 40 N
Load = ?
Load = Mechanical advantage × Effort
= 3 × 40 N
= 120 N

LEVER
Question 12.
Observe figure.

a) Name the position that supports the rod used as the simple machine.
(effort, load, fulcrum)
Answer:
fulcrum

b) Where is the fulcrum in common balance, seesaw, etc.?

Answer:
In the middle

Question 13.
A crowbar, beam of a common balance, seesaw, etc., are rigid rods. In all these, where is the load and effort?
Answer:
In crowbar, beam of a common balance, seesaw, etc., load is at one end and effort at the other end.

A lever is a rigid rod that can rotate around a fixed point called fulcrum.

Question 14.
What is the load arm here?
Answer:
The load arm here is 25 cm.

Question 15.
What is the perpendicular distance from the effort to the fulcrum known as?
Answer:
The perpendicular distance from the effort to the fulcrum known as the effort arm.

Question 16.
How much is the effort arm here?
Answer:
The effort arm here is 25 cm.

Question 17.
Change the loads and their positions and use appropriate efforts to bring the meter scale to equilibrium. Complete the table with the data obtained in each case.

Answer:

Question 18.
What inference can you arrive at from these activities?
Answer:
The inference that can be arrived at is that when a lever is in equilibrium, Load × Load arm = Effort × Effort arm.

When a lever is in equilibrium, Load × Load arm = Effort × Effort arm. This is the principle of a lever.

Question 19.
How can we calculate the mechanical advantage of a lever?
Answer:
Mechanical advantage = \(\frac{\text { Load }}{\text { Effort }}\)
According to the principle of the lever,
Load × Load arm = Effort × Effort arm
\(\frac{\text { Load }}{\text { Effort }}\) = \(\frac{\text { Effort arm }}{\text { Load arm }}\)
Mechanical advantage of levers = \(\frac{\text { Effort arm }}{\text { Load arm }}\)

Question 20.
You are given a meter scale, weights, a stand, a thread, and a mango. Find out and present how to
determine the mass of the mango.
Answer:
Suspend a meter scale at the centre of gravity. Suspend the mango at a fixed distance from that point. On the opposite side, at the same distance from the pivot, suspend the required weight to balance it. That will be the weight of the mango.

Question 21.
Is the fulcrum in a lever always between the load and the effort?
Answer:
No

Levers can be classified into three types based on the relative positions of the fulcrum, effort, and load. * First Order Lever * Second Order Lever * Third Order Lever

First Order Lever
Question 22.
Observe figure 7.11(a). What is the position of the fulcrum?

Answer:
The position of the fulcrum is in between the load and the effort.
First order lever

If the fulcrum is in between the load and the effort, it is a first order lever.Examples: common balance, scissors, seesaw.

Question 23.
In a common balance, the effort arm and the load arm are(equal/not equal).
Answer:
equal
Hence the load and effort will be equal.

Question 24.
What about while using scissors?
Answer:
In scissors the effort arm and load arm can vary depending on the use of the scissors.

Question 25.
While using a crowbar to move a stone, as shown in figure 7.11 (a), should you increase the effort arm or the load arm to enhance the mechanical advantage?
Answer:
While using a crowbar to move a stone, we should increase the effort arm to enhance the mechanical advantage.

Question 26.
What is the mechanical advantage in this case? (greater than one, one, less than one)
Answer:
greater than one

Question 27.
If the length of the load arm is increased more than the length of the effort arm, what will the mechanical advantage be?
(greater than one, one, less than one)
Answer:
less than one

Question 28.
Complete table 7.2 with the appropriate terms from the brackets.
(load is more than the effort, load and effort are equal, load is less than the effort)

Answer:

If the mechanical advantage is less than one	load is more than the effort
If the mechanical advantage is one	load and effort are equal
If the mechanical advantage is greater than one.	load is less than the effort

Question 29.
Write down examples for first order levers from daily life situations.
Answer:
Fixed pulley, common balance, scissors, seesaw, pliers, human elbow

Second Order Lever
Question 30.
Observe figure 7.13

a) Mark the position of the load, fulcrum, and effort in the figure.
Answer:

b) Where is the position of the load in the figure?
Answer:
The load comes in between the effort and the fulcrum

If the load comes in between the effort and the fulcrum, it is a second order lever. Examples: Lemon squeezer, nut cracker, bottle opener, staplers, wheelbarrows

Question 31.
Mark the load, fulcrum, and effort in the pictures given below.

Answer:

Question 32.
Where will the fulcrum in a second order lever be?
Answer:
At one end

Question 33.
What about the position of the load?
Answer:
The load comes in between the effort and the fulcrum.

Question 34.
Which of the following is correct in a second order lever?
(effort arm and load arm are equal, effort arm is longer than the load arm, effort arm is shorter than the load arm)
Answer:
Effort arm is longer than the load arm

Question 35.
The mechanical advantage of second order levers will always be
(less than one, one, greater than one)
Answer:
greater than one

Question 36.
Write down more examples for second order lever from daily life situations.
Answer:
Lemon squeezer, nut cracker, bottle opener, staplers, wheelbarrows

Third Order Lever
Question 37.
Observe figure 7.16 and mark the load, effort, and fulcrum.

Answer:

If the effort comes in between the load and the fulcrum, it is a third order lever. Examples: Tools used to pick sweets in bakeries, forceps, Tongs

Question 38.
In third order levers, which arm is longer?
(load arm, effort arm)
Answer:
load arm

Question 39.
What will be the mechanical advantage of a third order lever?
(less than one, one, greater than one)
Answer:
less than one

Question 40.
Write down more examples for third order levers from daily life situations.
Answer:

1. Fishing pole
2. Broom
3. ’ Tweezers
4. ’ Tools used to pick sweets in bakeries
5. ’ Forceps
6. ’ Tongs

Question 41.
The effort is greater than the load in a third order lever. If so, what is the advantage of using a third order lever?
Answer:
The advantage is that it helps to handle objects safely with ease.

Question 42.
Mark the fulcrum, load and effort in the case of a forceps.
Answer:

Question 43.
Complete the table

Answer:

Order of a lever	Relative position of fulcrum, load and effort	Mechanical advantage
First order	Fulcrum is in between the load and the effort	Greater than one /equal to one/less than one
Second order	Load is in between the fulcrum and the effort	Alwavs greater than one
Third order	Effort is in between the load and the fulcrum	Alwavs less than one

Fixed Pulley
Question 44.
What are fixed pulleys?
Answer:

Fixed pulleys are pulleys that rotate around a stationary axle. A fixed pulley can be imagined as many spokes rotating around a central pivot named fulcrum. In these spokes, the position where the load is experienced is marked as L and the position where the effort is applied is marked as E. In this, the effort arm and the load arm are the radii of the pulley.

Question 45.
What type of lever a fixed pulley is?
Answer:
A fixed pulley is similar to a first order lever.

Question 46.
What will be the relation between the load arm and the effort arm of the pulley?
(load arm is longer, effort arm is longer, effort arm and load arm are equal)
Ans:
effort arm and load arm are equal

Question 47.
When we consider a fixed pulley without friction, we have to apply …………………………
(more effort than the load, less effort than the load, an effort equal to load)
Answer:
an effort equal to load

Question 48.
What will be the mechanical advantage of a fixed pulley?
(less than one, one, greater than one)
Answer:
one

Question 49.
What is the advantage of using friction less fixed pulley to lift objects? Choose the correct option from those given below.
(can reduce the magnitude of the applied force / can change the direction of the applied force)
Answer:
can change the direction of the applied force

Question 50.
In a movable pulley the effort and the fulcrum are at either ends and the load is at the middle. Which is the order of this lever?
Answer:
Second order lever

Question 51.
Which is the load arm and effort arm?
Answer:
Load arm = Radius of the pulley
Effort arm = Diameter of the pulley

Question 52.
What is the mechanical advantage of a movable pulley?
Answer:
Mechanical advantage
= \(\frac{\text { Effort arm }}{\text { Load arm }}\) = \(\frac{\text { Diameter of the pulley }(2 r)}{\text { Radius of the pulley }(r)}[latex]
= 2

Question 53.
The mechanical advantage of a single movable pulley is 2. If so, how many times of the load to be lifted should the applied effort be?
Answer:
Half

Question 54.
The rope is pulled 2 m by applying effort. How much will the load rise?
Answer:
The load rises only one metre.

Question 55.
What should be the displacement of the rope, when the effort applied raises the load by 1 m?
(1 m, 2 m, 0 m)
Answer:
2 m

Question 56.
Is there a gain in work when the applied effort is halved? Prove.
Answer:
There is no gain in work when the applied effort is halved
Work, W = Fs
When the effort is reduced by half, the displacement produced by it is doubled.
That is, W = (F/2) × 2s = Fs. That is there is no change in the quantity of work done. No gain in work is achieved while using a movable pulley.

Question 57.
A movable pulley is used to lift 600 N load. When the rope is pulled 8 m by applying a force of 300 N then the load raises by 4 m. Prove that there is no gain in the work even though there is a gain in the effort applied.
Answer:
The displacement of the object, s = 4 m
Weight of the object, F = 600 N
Work done on the object
= F × s
= 600 × 4 = 2400 J
The displacement of the rope on applying 300 N force,
s₁ = 8 m
F₁ = 300N

The work done by the force we applied = F₁ s₁
= 30o × 8 = 2400 J
The work done on the object and the work done by the effort are equal.

Question 58.
Is there a gain in work by using simple machines?
Answer:
There is no gain in work by using simple machines.

Question 59.
The radius of the wheel is R and the radius of the axle is r. When the wheel is rotated once, What will be the distance moved by a point on the wheel’s circumference?
Answer:
When the wheel is rotated once, the distance moved by a point on the wheel’s circumference be 2πR.

Question 60.
What will be the distance moved by the object tied to the rope attached to the axle? (2πR / 2πr)
Answer:
2πr

Question 61.
What is the distance moved by the point on the wheel when rotated once due to the effort applied (E)?
Answer:
The distance moved by the point on the wheel when rotated once due to the effort applied (E) is 2πR.

Question 62.
What is the distance moved by the load?
Answer:
The distance moved by the load is 2πr.
The work done by the effort and the work done by the load are equal here.
Work done by the effort = Work done by the load
Work done = Fs
E × 2πR = L × 2πr
= L/E = R/r
Since the radius of the wheel is larger and the radius of the axle is smaller, the mechanical advantage of wheel and axle will be greater than one.
As the radius of the wheel increases, the mechanical advantage also increases.

• The train bogies were slowly lifted by turning the wheel using long levers.

Gear

Question 63.
What are gears? What are the uses of these gears?
Answer:
A gear is a mechanical device used in machines.
They are used to transfer motion or force from one part of the machine to another.

Question 64.
What is the main part of a gear system?
Answer:
The main part of a gear system is the system of two interlocking toothed wheels.
In gears, energy is transferred from a large toothed wheel to a small toothed wheel or from a small toothed wheel to a large toothed wheel.

Question 65.
When the large toothed wheel rotates once, how many times will the small toothed wheel rotate? (once, more than once, less than once)
Answer:
more than once

Question 66.
What changes will this cause in the speed of the second toothed wheel?
Answer:
The speed of the second toothed wrheel increases.

Question 67.
A toothed wheel is attached to the engine of most of the vehicles. What is the function of this toothed wheel?
Answer:
This toothed wheel is connected to a system of wheels of different sizes attached to the axle which transfers motion to the tyres.

Question 68.
Which wheel is connected to the toothed wheel attached to the engine to increase the speed of the vehicle?

To increase the speed of the vehicle, the toothed wheel attached to the engine must be connected to
the small toothed wheel that helps to turn the tyre of the vehicle.

Question 69.
Which wheel is connected to the toothed wheel attached to the engine while going uphill?
(small/large)

Answer:
large

Question 70.
What is the advantage of connecting the large wheel to the toothed wheel attached to the engine while going uphill?
Answer:
The speed of the vehicle decreases, but its efficiency to rotate increases.

Question 71.
What happens to the speed of the large toothed wheel when energy is transferred from the small toothed wheel to the large toothed wheel? (Increases/decreases)
Answer:
decreases

Question 72.
Try lifting the same object to the same height using inclined planes of different lengths. When did it feel easier?
Answer:
It felt easier when using inclined plane of more length.

Question 73.
An object is to be lifted to a height h metre by pushing along an inclined plane of length l metre. Here, what is the work done by the effort?
Answer:
If the effort is E and the load is L, then the work done by the effort E to move it over a distance,
l = (F_s) = El

Question 74.
An object is to be lifted to a height h metre by pushing along an inclined plane of length 1 metre.
Here, what is the work done by the load?
Answer:
Work done by the load L to lift to a height h is Work = Force × Displacement
i.e., Weight × height = Lh

Question 75.
An object is to be lifted to a height h metre by pushing along an inclined plane of length 1 metre. Here, what is the mechanical advantage?
Answer:

Question 76.
Does using a longer inclined plane or a shorter inclined plane provide more mechanical advantage?
Answer:
Mechanical advantage = [latex]\frac{\text { Length of inclined plane }}{\text { Height of inclined plane }}\)
So, using a longer inclined plane provides more mechanical advantage.

Question 77.
Inclined planes are often used in situations where objects are to be lifted.
a) What is the work done to lift a 600 N load by 3 m?
b) The force applied was 200 N along an inclined plane to lift this load. Displacement of the load was 9 m. What is the work done?
c) Is there a gain in the work done?
Answer:
a) Force, F = 600 N
Displacement, s = 3 m
Work done, W = Fs = 600 × 3 = 1800 Nm= 1800 J

b) Force, F = 200 N
Displacement, s = 9 m
Work done, W = Fs = 200 × 9 = 1800 Nm= 1800 J

c) There is no gain in work done.

Question 78.
What are the ways to increase the mechanical advantage of an inclined plane?
Answer:
We can increase the length of an inclined plane to increase the mechanical advantage.

Question 79.
Why are long inclined roads built in hairpin roads on ghats and other such places?


Answer:
The concept of mechanical advantage of inclined plane is utilised here. As we increase the length of an inclined plane the mechanical advantage increases. So the inclined roads are built with maximum length.
• It is understood that large heavy stones were taken up to build the pyramids using inclined roads.

Question 80.
Observe the wedges of different length and thickness. Which of these is easier to use? Why?

Answer:
Fig. 7.32 (c),

The wedge in figure 7.32 (c) has less thickness and more length. So, its mechanical advantage is greater than that of others. If a wedge is made longer and thinner, it will be easier to use.

Question 81.
Write down the use of a screw jack.
Answer:
A screw jack is used to lift vehicles to change a tyre or for minor repairs.

Question 82.
A 600 kgwt load is lifted by 4 m along an inclined plane of length 8 m. Calculate the mechanical advantage. What force must be applied along the inclined plane?
Answer:
Mechanical advantage of an inclined plane

Question 83.
Label the name of the simple machines given below.

Answer:

The bicycles and sewing machines we use today are often said to be the simplest machines. But they are a combination of many types of the simple machines mentioned above.

Std 10 Physics Chapter 7 Notes – Extended Activities

Question 1.
Plan a project to find the density of a meter scale.
Answer:
Find the centre of gravity of the meter scale. Hang the scale at a distance of 10 cm, 20 cm, 30 cm from the centre of gravity and determine the position required to balance it in each case.

Assuming the mass of the part that is 1 cm as m. Using the equation load × load arm = effort × effort arm, the mass of the scale and the density of it can be found out. When balancing it at 10 cm, the load = 60 × m
load arm = 30 cm
Effort = 40 × m + suspended mass (y)
load × load arm = 60 × m × 30
Effort × Effort arm = 40m × 20 + y × x (distance from the suspended mass ‘y’ to the fulcrum). Find the value of x, for a value of y (say 50 g or 100 g). Repeat the experiment by hanging the scale at different distances (as mentioned above 20 cm, 30 cm from the centre of gravity).
Solve for the mass from the euqation.
Find 100 × m = M, to find the total mass of the meter scale.

Measure the Length, breadth (b) and thickness (t) (dimensions) of the meter scale.
Calculate volume V= Length × Breadth × Thickness and calculate density using the formula
Density = \(\frac{M(\text { mass })}{V(\text { Volume })}\)

Question 2.
Observe a bicycle and list the simple machines that forms a part of it.
Answer:

1. Wheel and axle
2. Lever
3. Pulley
4. screw
5. Inclined plane

Mechanical Advantage in Action Class 10 Notes

Mechanical Advantage in Action Notes Pdf

• Devices that make exertion easier are called simple machines.
• Simple machines are devices that change the magnitude of the effect of force or the direction of the force or both.
• There are mainly six types of simple machines. They are:
  Lever, Pulley, Wheel and axle, Inclined plane, Screw and Wedge
• Mechanical advantage (MA) is the ratio of the load to the effort. It is a number indicating how many times of the load is the effort. Mechanical advantage is only a ratio. It has no unit.
  Mechanical advantage, MA = \(\frac{\text { Load }}{\text { Effort }}\)
• Centre of gravity is the point at which the entire weight of an object is considered to act.
• When a lever is in equilibrium, Load × Load arm = Effort × Effort arm. This is the principle of a lever.
• Levers can be classified into three types based on the relative positions of the fulcrum, effort, and load.
  • First Order Lever
  • Second Order Lever
  • Third Order Lever
• First order lever: In a first order lever, fulcrum comes in between effort and load. The mechanical advantage of a first order lever is equal to one or greater than one or lesser than one.
• Second order lever: The load comes in between effort . and fulcrum. Mechanical advantage of a second order . lever is always more than one.
• Third order lever: The effort comes in between fulcrum and load. Its mechanical advantage is always less than one.
• A Pulley is a simple machine. It is of two types:
  1. Fixed pulley
  2. Movable pulley
• In wheel and axle systems, the wheel is rotated by applying force (Effort) to it. When the wheel is rotated once, the axle also rotates once.
• Since the radius of the wheel is larger and the radius of the axle is smaller, the mechanical advantage of wheel and axle will be greater than one.
• A gear is a mechanical device used in machines. They are used to transfer motion or force from one part of the machine to another. The main part of a gear system is the system of two interlocking toothed wheels.
• A wedge is a double inclined plane.
• A screw jack is used to lift vehicles, to change a tyre or for minor repairs.

INTRODUCTION

Simple machines are basic mechanical devices that make work easier by changing the magnitude or direction of a force. Even the bicycles and sewing machines we use today are often said to be the simplest machines. Simple machines are the building blocks of more complex machines and have been used for centuries to perform tasks more efficiently. There are six classic simple machines. They are lever, pulley, wheel and axle, inclined plane screw and wedge. These machines operate on the principle of mechanical advantage, allowing a smaller force to move a larger load or perform tasks with less effort. They are fundamental in everyday tools and complex machinery, simplifying tasks like lifting, cutting, or moving objects. This unit deals with the basic ideas about simple machines.

Simple machines

• Devices that make exertion easier are called simple machines.
• Advantage of using simple machines.
  • Changes the magnitude of the effect of the force.
  • Changes the direction of the applied force.
• Simple machines are devices that change the magnitude of the effect of force or the direction of
  the force or both.
• There are mainly six types of simple machines. They are lever, pulley, wheel and axle, inclined plane, screw and wedge.
• The force we apply to a simple machine is the effort (E). The force the simple machine has to overcome is the load (L).
• Mechanical advantage (MA) is the ratio of the load to the effort. It is a number indicating how many times of the load is the effort. Mechanical advantage is only a ratio. It has no unit.

Mechanical advantage, MA = \(\frac{\text { Load }}{\text { Effort }}\)

Lever

• A lever is a rigid rod that can rotate around a fixed point called fulcrum.
• Centre of gravity is the point at which the entire weight of an object is considered to act.
• Levers can be classified into three types based on the relative positions of the fulcrum, effort, and load.
  • First Order Lever
  • Second Order Lever
  • Third Order Lever
• When a lever is in equilibrium,
  Load × Load arm = Effort × Effort arm. This is the principle of a lever.
  Mechanical advantage of levers = \(\frac{\text { Load }}{\text { Effort }}\) = \(\frac{\text { effort arm }}{\text { load arm }}\)
• If the fulcrum is in between the load and the effort, it is a first order lever.
  Examples: common balance, scissors, seesaw.
• The mechanical advantage of first order lever can be greater than one /equal to one/less than one.
• If the load comes in between the effort and the fulcrum, it is a second order lever. Examples: Lemon squeezer, nut cracker, bottle opener, wheelbarrows
• The mechanical advantage of second order levers will always be greater than one.
• If the effort comes in between the load and the fulcrum, it is a third order lever. Examples: Tools used to pick sweets in bakeries, forceps, Tongs
• The mechanical advantage of third order lever will be always less than order one.

Pulley

• Pulley is a simple machine. It is of two types. Fixed pulley and movable pulley.
• Fixed pulleys are pulleys that rotate around a stationary axle. A fixed pulley can be imagined as many spokes rotating around a central pivot named fulcrum. In these spokes, the position where the load is experienced is marked as L and the position where the effort is applied is marked as E. In this, the effort arm and the load arm are the radii of the pulley.
• Mechanical advantage of a fixed pulley is one
• When effort is applied on a movable pulley, the pulley and the load will be lifted upwards along the other side of the rope. This lifting is caused by the rotation of the pulley along the rope.
• Mechanical advantage of a movable pulley is 2 Mechanical advantage = \(\frac{\text { Diameter of the pulley (2r) }}{\text { Radius of the pulley (r) }}\)

Wheel and axle

• In wheel and axle systems, the wheel is rotated by applying force (Effort) to it. When the wheel is rotated once, the axle also rotates once. If the radius of the wheel is R and the radius of the axle is r, and when the wheel is rotated once, the distance moved by a point on the wheel’s circumference would be 2πR.
• Since the radius of the wheel is larger and the radius of the axle is smaller, the mechanical advantage of wheel and axle will be greater than one.
  Mechanical Advantage = \(\frac{\text { L(load) }}{\text { E (effort) }}\) = \(\frac{\text { Radius of wheel (R) }}{\text { Radius of axle (r) }}\)
• As the radius of the wheel increases, the mechanical advantage also increases
• A gear is a mechanical device used in machines. They are used to transfer motion or force from one part of the machine to another. The main part of a gear system is the system of two interlocking toothed wheels.

Inclined plane

• Mechanical advantage = \(\frac{\text { Length of inclined plane (l) }}{\text { Height of inclined plane(h) }}\)
• Using a longer inclined plane provides more mechanical advantage.

Wedge

• A wedge is a double inclined plane. Household tools like knife, axe, and work tools like chisel are variants of wedges.
• Mechanical advantage of a wedge \(\frac{\text { length of the inclined plane of the wedge }(l)}{\text { thickness of the wedge }(\mathrm{h})}\)

Screw

• A screw can be considered as an inclined plane. The distance between two consecutive threads is the pitch of a screw.
• The mechanical advantage of a screw = length of the inclined plane (l) / height of the inclined plane (h) = length of one thread (l) / pitch (h)

You may have seen loading a lorry using an inclined plane.
• When it is difficult to climb stairs, we use ramps. From this, it is understood that inclined planes are used to reduce exertion.
Devices that make exertion easier are called simple machines.

SIMPLE MACHINES
Let’s examine the ways in which simple machines make exertion easier.

TYPES OF SIMPLE MACHINES
LEVER
Activity to understand the principles related to levers
Suspend a wooden meter scale on a stand. Balance it as shown in figure 7.8.

Identify the point at which it is to be balanced.

Entire weight of the meter scale act through this point. This point is the centre of gravity of the meter scale. The meter scale can be suspended or pivoted along a perpendicular line passing through the centre of gravity as shown in the figure.

You can balance a book on the tin of your finger

A book can be balanced when it is pivoted on the perpendicular line passing through its centre of gravity.
Centre of gravity is the point at which the entire weight of an object is considered to act

Activity to understand the principles related to levers

Suspend a wooden meter scale along a perpendicular line passing through the centre of gravity as shown in the figure on a stand. Balance it as shown in figure. Suspend a mass of 50 g at a distance of 25 cm from the balancing point on one side of the meter scale. Suspend another mass of 50 g on the other side of the meter scale to balance it.

The weight suspended first is considered as the load. The perpendicular distance from the load to the fulcrum is the load arm. The weight suspended or the force applied to produce equilibrium in the rod is the effort.

PULLEY
A Pulley is a simple machine. It is of two types:
1. Fixed pulley
2. Movable pulley

Movable Pulley

When effort is applied on a movable pulley, the pulley and the load will be lifted upwards along the other side of the rope. This lifting is caused by the rotation of the pulley along the rope.

WHEEL AND AXLE
There were instances when modern machines failed to lift train bogies that had fallen into a lake. But they were brought ashore using a wheel and axle.

In wheel and axle systems, the wheel is rotated by applying force (Effort) to it. When the wheel is rotated once, the axle also rotates once.

INCLINED PLANE
You may have seen an inclined plane being used to load large logs, machine parts, etc., on to a lorry.

WEDGE
A wedge is a double inclined plane. Household tools like knife, axe, and work tools like chisel are variants of wedges.

SCREW JACK
A screw can be considered as an inclined plane. The distance between two consecutive threads is the pitch of a screw.

Activity to explain pitch of a screw.
Cut a paper in the shape of an inclined plane. Colour its slanting edge. (Fig 7.35(a))
Wrap this paper around a cylindrical pencil. (Fig.7.35(b))

The vertical distance from the beginning of the slanting edge of the paper (P) to where one full turn is completed (Q) is the pitch (h). That is, the distance between two consecutive threads is the pitch.

Activity to explain the length of one thread of a screw
Cut a paper in the shape of an inclined plane. Colour its slanting edge. (Fig.7.35(a))

Wrap this paper around a cylindrical pencil.(Fig.7.35(b)) Unwrap the paper and straighten it. Measure the distance from P to Q (Fig.7.35(c)). This Distance is the length of the thread PQ (l). That is the length of one thread of a screw.

The mechanical advantage of a screw = length of the inclined plane (l) / height of the inclined plane (h) = length of one thread (l) / pitch (h)

The comprehensive approach in SCERT Class 10 Physics Solutions Chapter 6 Electromagnetic Induction in Daily Life Important Questions with Answers ensure conceptual clarity.

SSLC Physics Chapter 6 Important Questions Kerala Syllabus

Electromagnetic Induction in Daily Life Class 10 Important Questions

Question 1.
When there is a change in magnetic flux linked with a conductor, an emf is induced in it. Name the phenomenon?
Answer:
Electromagnetic Induction

Question 2.
The secondary coil of a transformer has double turns than its primary coil. If the voltage applied in the primary coil is 25 V, what will the voltage be in the secondary?
(25 V, 50 V, 2 V, 12.5 V)
Answer:
50 V

Question 3.
What is the energy conversion taking place in a windmill?
Answer:
Wind Energy → Mechanical Energy → Electrical Energy

Question 4.
Statement: A current is induced in a coil when a magnet is moved towards or away from it
Reason: The/elative motion between the coil and the magnet changes the magnetic flux through the coil
(a) Both statement and reason are true; the reason explains the statement.
(b) Both statement and reason are true; but the reason does not explain the statement.
(c) Both the statement and the reason are incorrect.
(d) Statement is incorrect; reason is correct.
Answer:
(a) Both statement and reason are true; the reason explains the statement.

Question 5.
Some characteristics of stepup transformers is given below. Select the correct statements suitable for stepup transformers.
(a) Secondary voltage is greater than primary voltage.
(b) Thick wires are used in the secondary.
(c) Primary voltage is greater than secondary voltage.
(d) The current in the primary coil is greater than that in the secondary coil.
(i) (a), (b) and (d)only
(ii) (a) and (d) only
(iii) (a) and (c) only
(iv) (b) only
Answer:
(ii) (a) and (d) only

Question 6.
Write any two precautions to be taken to avoid electric shock.
Answer:

• Never handle electric equipment or operate switches when the hands are wet.
• Do not fly kites near electric lines.

Question 7.
The primary and secondary currents of a transformer are 2 A and 4 A respectively. The output voltage of this transformer is 100 V.
(a) Identify the transformer.
(b) Calculate the primary voltage of the transformer.
Answer:
(a) Stepdown Transformer

(b) V_P × Ip = Vs × Is
∴ V_P = (Vs × Is) / Ip
= (100 × 4) / 2
= 200 V

Question 8.
The current in the secondary coil of a transformer with no power loss is 5 A and that is the primary is 0.5 A.
(a) What type of transformer is this?
(b) If the input voltage of this transformer is 240 V calculate the output voltage.
Answer:
(a) Step down transformer

(b) I_S = 5 A
I_P = 0.5 A
V_P = 240 V
V_P = ?
I_S × V_S = I_P × V_P
V_S = \(\frac{V_P \times I_P}{I_S}\) = \(\frac{0.5 \times 240}{5}\) = 24 V

Question 9.
Fuse, MCB, ELCB, and RCCB are used to ensure safety in household electric circuits.
(a) What is the difference between the functioning of Fuse and MCB?
(b) What is the advantage of MCB over Fuse?
(c) What is the function of ELCB and RCCB in electric circuits?
Answer:
(a) Fuse – In fuse, fuse wire melts due to excess current. It works based on the heating effect of electric current.
MCB – It has an internal switch that gets tripped when there is excess current. It works based on the magnetic effect and the heating effect of electrical energy.

(b) In MCB, after solving the problem, the switch can be turned on. But in the fuse, the melted fuse wire is to be replaced by another suitable wire. Moreover, MCB is more sensitive than fuse. MCB is simple to resume the supply.

(c) ELCB helps to break the circuit automatically when there is leakage of current due to insulation failure or short circuit, it protects the user from electric shock. RCCB also breaks the circuit, so that there’is no harm due to electric shock. RCCB ensures more safety.

Question 10.
A transformer has 100 turns in the primary and 1000 turns in the secondary.
(a) Which coil of this transformer is made using thick wire? Give reason.
(b) Explain/how electrical energy is transferred from the primary to the secondary of the transformer
Answer:
(a) Primary coil is made using thick wire.
(Hint: Number of turns is less in the Primary here. So it is a step-up transformer. So thick wire is used in the primary coil)
When the thick wire is used, the resistance of the coil can be minimized. There are two benefits to this.
(i) Overheating of the coil can be prevented.
(ii) Energy loss can be minimized.

(b) It is through mutual induction power is transferred from the primary coil to the secondary coil.
When the strength or direction of the current in one of the two adjacent coils changes, the magnetic flux around it changes. As a result, an emf is induced in the secondary coil. This phenomenon is mutual induction.

Question 11.
AC generators are used in power stations in our Country.
(a) What is the voltage produced by the generators in our power stations?
(b) What do you mean by transmission loss?
(c) Explain how it is minimized.
Answer:
(a) 11000 V (11 kV)

(b) When electrical energy is transmitted through conducting wires, energy is wasted in the form of heat.

(c) As H = I²Rt, for reducing H, I and R are to be decreased.
As P = VI, For decreasing I without affecting the power, voltage V is to be increased before transmission.

Question 12.
A schematic diagram of a generator is given:

(a) Which type of generator is this? (AC/DC)
(b) Name the parts of this generator marked as
(c) State the working principle of this device.
1, 2, 3, 4,
1. ________________
2. ________________
3. ________________
4. ________________
(c) State the working principle of this device.
Answer:
(a) AC Generator

(b) 1. Field magnet
2. Armature
3. Slip rings
4. Brush

(c) Electromagnetic induction: Whenever there is a change in the magnetic flux linked with a coil, an emf is induced in the coil. This phenomenon is electromagnetic induction.

Question 13.
Observe the circuit of household electrification.

(a) Which device is used to measure the electrical energy consumed in household circuits?
(b) Write any two advantage of connecting the devices in parallel in a household circuit.
(c) Write the function of ELCB.
Answer:
(a) Watt-hour meter.
(b) Devices work according to the marked power.
Devices can be controlled using switches as needed.

(c) ELCB helps to break the circuit automatically whenever there is a current leak due to insulation failure or other reasons.

Question 14.
A transformer without power loss works at an input of 250 V. A current of 1 A flows through the secondary coil when an electrical device of power 50 W is connected to the secondary.
(a) Which type of transformer is used here?
(b) What is the working principle of a transformer?
(c) Calculate the current through the primary.
Answer:
(a) Ps = Vs × Is
50 = Vs × 1
Vs = 50 V
Since Vs is less than Vp, it is a step-down transformer.

(b) Mutual Induction

(c) Vp × Ip = Vs × Is
Vp = 250 V, Vs = 50 V
Is = 1 A
Ip = (Vs × Is) / Vp = (50 × 1) / 250 = 0.2 A

Question 15.
Analyze the following schematic diagram and answer the questions.

(a) Name the device.
(b) Which are the main parts of this device?
(c) Illustrate the graphic representation of the output when the field magnet is rotated by keeping the armature stationary.
Answer:
(a) DC Generator.

(b) Armature, field magnet, split ring commutator, and brushes.

(c)

The comprehensive approach in SCERT Class 10 Physics Solutions Chapter 5 Electric Energy: Consumption and Conservation Important Questions with Answers ensure conceptual clarity.

SSLC Physics Chapter 5 Important Questions Kerala Syllabus

Electric Energy: Consumption and Conservation Class 10 Important Questions

Question 1.
If intensity of electric current in a circuit is doubled the heat energy developed in this circuit increases _______________ times.
(2,12,4,14)
Answer:
4
Hint: Heat produced is directly proportional to the square of current. If current is doubled, heat energy will be increased to four times.

Question 2.
Which among the following is the energy transformation taking place when a storage battery is being charged?
a) chemical energy to electrical energy.
b) electrical energy to heat energy.
c) electrical energy to chemical energy.
d) magnetic energy to electrical energy.
Answer:
c) electrical energy to chemical energy

Question 3.
Some statements related to activities to be done to reduce carbon footprint is given
i. Increase domestic energy consumption.
ii Avoid wasting food.
iii. Use public transport.
iv. Reduce the use of reusable products.

Which are the correct statements related to it?
A. i and ii only
B. iv only
C. All are correct
D. ii and iii only
Answer:
D. ii and iii only

Question 4.
Some statements related to electrical power is given.
i. Electric power is measured in joules.
ii 1 kilowatt-hour is equal to 1000 joules.
iii Power is the quantity of work done by an electrical appliance per unit time.
iv. Power, P = \(\frac{V}{I}\)
Which are the correct statements related to it.
a) i and ii only
b) iii and iv only
c) iv only
d) iii only
Answer:
d) iii only

Question 5.
Statement: A heater A operating at 230 V draws 2 A current, its power obtained is 460 W.
Reason: The power can be calculated as the, product of voltage and current.
a) Statement and reason are correct; the reason explains the statement.
b) Statement and reason are correct; however, the reason does not explain the statement.
c) both the statement and the reason are incorrect.
d) Statement is incorrect; reason is correct
Answer:
a) Statement and reason are correct; the reason explains the statement.

Question 6.
The heat generated in a current carrying conductor can be explained by a famous law.
a) Write the name of this law.
b) Write the mathematical equation for this law, explain each letters used in the equation.
Answer:
a) Joule’s law

b) H = I²Rt or H ∝ I² Rt
H – Heat generated in a conductor
I – Intensity of electric current
R – Resistance of the conductor
t – time for which current flows

Question 7.
Resistance of a 230 V heating device is 460 Ω. Calculate the heat energy produced by it in 10 minutes.
Answer:
H = \(\frac{V^2 t}{R}\)t, t = 10 × 60 s, R = 460 Ω
= \(\frac{230^2}{460}\) × 600 = 69000 J
H = 69000J

Question 8.
a) Name the part of a heating equipment in which the electric energy is converted into heat energy.
b) Name the substance used to make this part.
Answer:
a) Heating coil
b) Nichrome

Question 9.
In a house, 5 CF lamps each of 20 W work for 4 hours, and 4 fans each of 60 W work for 5 hours in a day. What will be the daily consumption of energy shown by the watt-hour meter?
Answer:
Electric energy (in kilowatt hour) = \(\frac{\text { Power in watt × time in hour }}{1000}\)
Energy consumed by 5 CF lamps = \(\frac{5 \times 20 \times 4}{1000}\) = 0.4 kWh
Energy consumed by 4 fans = \(\frac{4 \times 60 \times 5}{1000}\) = 1.2 kWh
Daily consumption of energy
= 0.4 + 1.2 = 1.6 kWh
= 1.6 units

Question 10.
How many units of energy will be consumed by a 100 W bulb in 30 days, if it works 10 hours everyday?
Answer:
Electric energy (in kilowatt hour) = \(\frac{\text { Power in watt × time in hour }}{1000}\)
Energy consumed by bulb in a day
= \(\frac{1 \times 100 \times 10}{1000}\)
= 1 unit
Energy consumed by bulb in a month
= 1 × 30 = 30 units

Question 11.
The government is promoting the installation of solar panels by giving incentives to boost electricity generation. Explain its significance in the context of the energy crisis.
Answer:
The over use of non-renewable fossil fules like coal, oil, and natural gas which contribute to pollution and global warming has resulted in an energy crisis for the entire world.

Because it is abundant, renewable, environmentally friendly, and accessible even in remote locations, solar energy is an excellent substitute. Solar thermal power plants use the sun’s heat to produce electricity, whereas solar cells directly turn sunlight into electrical power. In everyday life, gadgets like solar water heaters and stoves can help cut down on the amount of power and fossil fuels-used. We can lessen the effects of the energy crisis, conserve resources, and safeguard the environment by utilising more solar energy.

Question 12.
100W bulb works on 230V supply.
a) If voltage is halved, how much will be the power?
b) If voltage decreases to 1/4 times, how much will be the power?
c) If the voltage is doubled what happen to the bulb?
Answer:
a) R = \(\frac{\mathrm{V}^2}{\mathrm{P}}\) = \(\frac{230^2}{100}\) = 529
V = 115 V (voltage is halved)
P = \(\frac{\mathrm{V}^2}{\mathrm{R}}\) = \(\frac{115^2}{100}\) = 25 W
(When voltage is halved, power becomes 1/4 times the original power)
P = 25 W

b) V = 57.5 V (Voltage decreases to 1/4 times)
P = \(\frac{57.5^2}{529}\)
P = 6.25 W

c) Device will be damaged due to high voltage.

Question 13.
Fill in the blanks of the table suitably.

Device	Energy change	Effect of electricity
Electric bulb	(a)	Lighting effect
(b)	Electrical energy is converted to heat energy	(c)
Mixie	(d)	Mechanical effect
Electric kettle	(e)	(f)

Answer:
(a) – Electrical energy,
(b) – Electric Iron,
(c) – Heating effect,
(d) – Electric energy to mechanical energy,
(e) – electrical energy to heat energy,
(f) – heating effect.

Question 14.
A heating coil with 60 Ω resistance is connected to a 240V supply.
a) Calculate the power of the appliance.
b) Calculate the amount of heat generated by this heating coil in 5 minutes.
c) If this appliance continuously work for 10 hours, calculate the energy consumed in commercial units.
Answer:
a) Power of the appliance
P = \(\frac{\mathrm{V}^2}{\mathrm{R}}\) = \(\frac{240^2}{60}\) = 960 W

b) t = 5 min = 5 × 60 = 300 s
Heat generated = \(\frac{\mathrm{V}^2}{\mathrm{t}}\)
H = 960 × 300 = 288000 J

c) Electric energy (in kilowatt hour)
= \(\frac{\text { Power in watt } \mathrm{x} \text { time in hour }}{1000}\)
Electric energy = \(\frac{1 \times 960 \times 10}{1000}\) = 9.6 units

Question 15.
Energy conservation is very important for a better tomorrow.
a) What do you mean by energy crisis?
b) How do people contribute to energy crisis (any two)
c) Write two actions to reduce your daily electrical energy consumption, (any two)
Answer:
a) Energy crisis is the increase in demand for energy and the decrease in its availability.

b)

• Careless use of electricity at homes, transport, and industries
• Over dependence on fossil fuels like coal, oil, and natural gas
• Not making proper use of natural energy resources.
• Slow action and lack of awareness about saving energy

c)

• Make a transition to energy-efficient appliances.
• Use LED Bulbs-LEDs use less power and last longer than normal bulbs.
• Turn off electric appliances when not in use- Always switch off fans, lights, and appliances when you leave a room.
• Use natural light during the day

Question 16.
An electric heater has a resistance of 690 Ω and is designed to operate at 230 V.
(a) What are the characteristics of a good heating coil?
(b) Calculate the heat energy produced by this heater when it works for 30 minutes.
Answer:
Resistance, R = 690 Ω,
time, t = 30 minute = 30 × 60 = 1800 s
Voltage, V = 230 V

(a) Characteristics of a good heating coil are

• High oxidation resistance
• Ability to remain in red hot condition for a long time.
  • High melting point
  • High resistivity

(b) Heat generated,
H = \(\frac{V^2 t}{R}\) = \(\frac{230^2 \times 1800}{690}\) = 138000 J

Question 17.
An electric heater of 1000 Ω works on a 230 V supply
a) Write down the energy change taking place in the electric heater.
b) State the law to find the quantity of heat generated in an electric heater?
c) Calculate the electrical energy consumed when the heater works for three hours.
Answer:
a) Electrical energy is converted to heat energy

b) The quantity of heat produced in a current carrying conductor is directly proportional to the square of the current (I²), the resistance of the conductor (R) and the time (t) for which the current flows. This is Joule’s law.

c) V = 230V, R = 1000 Ω, t = 3 hour = 3 × 60 × 60 = 10800 s
H = \(\frac{V^2 t}{R}\) = \(\frac{230^2 \times 10800}{1000}\) = 571320J

Question 18.
Observe the figure.

a) Write down the name of the device.
b) What is it used for?
c) In a house 5 LED lamps each of 20 W works for 5 hours and one laptop of 50 W works for 2 hours daily.. Calculate electrical energy consumption in one month in commercial units.
Answer:
a) Watt-hour meter

b) The quantity of electric energy consumed in houses can be measured directly by a watt hour meter.

c) Electric energy (in kilowatt hour)
= \(\frac{\text { Power in watt × time in hour }}{1000}\)
Electric energy consumed by lamps
= \(\frac{5 \times 20 \times 5}{1000}\) = 0.5 units
Electric energy consumed by laptop
= \(\frac{1 \times 50 \times 2}{1000}\) = 0.1 units
Total energy consumption in a day
= 0.5 + 0.1 = 0.6 units
Total energy consumption in a month
= 0.6 × 30 = 18 units

Question 19.
The figure shows two heating coils connected in an electric circuit.

a) Find the current through each coil.
b) If current flows through the circuit for 5 minutes, which coil gets heated more? Find the heat
developed in that coil.
Answer:
a) V = 230 V, R = 115 Ω
Current through 115 Ω coil
I = \(\frac{V}{R}\) = \(\frac{230}{115}\) = 2 A
V = 230 V, R = 46 Ω
Current through 46 Ω coil
I = \(\frac{V}{R}\) = \(\frac{230}{46}\) = 5 A

b) The coil having 46 Ω. resistance gets heated up more (Even though V (voltage), t (time of current flow) is same in both coils, 46 Ω coil has less resistance, So more current flows through it and more heat energy is produced)
Heat energy produced in 46 Ω coil.

Question 20.
2 A current is drawn by a heating coil when 230 V potential difference is applied.
a) Which material is commonly used to make a heating coil?
b) What is the quantity of charge that flows through this coil in 5 minutes?
c) What is the resistance of the coil?
a) Find the current through each coil.
Answer:
a) Nichrome is used to the bating coil.

b) Charge (Q) = I × t = 2 × 300 = 600 C

c) Resistance (R) = \(\frac{V}{R}\) = \(\frac{230}{2}\) = 115 Ω

The comprehensive approach in SCERT Kerala Syllabus 10th Standard Physics Textbook Solutions and Class 10 Physics Chapter 6 Electromagnetic Induction in Daily Life Notes Questions and Answers English Medium ensure conceptual clarity.

SSLC Physics Chapter 6 Notes Questions and Answers Pdf Electromagnetic Induction in Daily Life

SCERT Class 10 Physics Chapter 6 Electromagnetic Induction in Daily Life Notes Pdf

SSLC Physics Chapter 6 Questions and Answers – Let’s Assess

Question 1.
Choose the correct answer from the brackets.
a) What is the working principle of a generator?
(motor principle, mutual induction, electro-magnetic induction, all of these)
b) What type of electricity is generated in the armature of a DC generator?
(AC, DC, current at constant voltage, none of these)
c) At what voltage is electricity generated in power stations in India?
(11 kV, 11 V, 110 V, 230 V),
d) What is the voltage of electricity supplied for household use in our state?
(230 V, 230 kV, 11 kV, 11 V)
Answer:
a) Working principle of a generator: Electromagnetic induction.
b) Type of electricity in DC generator armature: AC
c) Voltage generated in power stations in India: 11 kV
d) Voltage supplied for household use: 230 V

Question 2.
Observe the figure.

a) If the magnet is rapidly moved into the coil, what will you observe in the galvanometer?
b) What will be the nature of the current obtained if the magnet is rapidly moved up and down inside the coil?
c) What are the ways to increase the current induced in the coil?
d) By what name is this phenomenon known as?
Answer:
a) The galvanometer needle will deflect.

b) The current will be alternating (changes direction).

c)

• Moving the magnet faster
• Using a stronger magnet
• Using more turns of wire in the coil

d) This phenomenon is called electromagnetic 6. induction.

Question 3.
Classify the following that operate on AC and that on DC.
Torch, grinder, microwave oven, emergency lamp, calculator
Answer:

Operates on AC	Operates on DC
Grinder	Torch
Microwave oven	Emergency lamp
	Calculator

Question 4.
Observe the figure.

a) Which device is shown in the figure?
b) Name the parts marked X, Y, and Z.
c) Which type of current is obtained in the external circuit?
d) What is its working principle?
Answer:
a) AC Generator
b) X-Field magnet Y – Armature
Z -Slip ring

c) Alternating current (AC)

d) The working principle of AC Generator is Electromagnetic induction.

Question 5.
What are the problems faced while transmitting electricity over long distances using conducting wires? How can these problems be solved?
Answer:
Problems:

• Energy loss as heat due to the large current in wires
• Energy loss as heat due to the resistance in wires.
• Voltage drop over a long distances.

Solutions:

• Use high voltage to reduce the current.
• Use thick wires with low resistance.
• Use transformers to step up voltage for transmission and step down for distribution purpose.

Question 6.
Observe the figure.

a) Which line is the red coloured wire?
b) To which part of the appliance is the green coloured wire connected ?
c) What is the advantage of connecting a three pin plug to appliances?
Answer:
a) Phase

b) Earth (to ground) connection of the appliances.

c) Advantages of connecting a three-pin plug to appliances:

1. Prevents electric shock by using the earth wire.
2. Protects appliances from damage due to extra current.
3. Ensures proper current flow through live and neutral wires.
4. Works with MCB or fuse to stop faults safely.

Question 7.
Write down any 4 precautions to avoid electric shock.
Answer:

1. Do not handle electrical appliances or operate switches with wet hands.
2. Plug into or unplug from a socket only after turning off the switch.
3. Do not operate high power appliances in a normal socket.
4. Do not touch the inside of a cable TV adapter. Ensure that the adapter has an insulator cover.
5. Do not fly kites near power lines.

Question 8.
A transformer has 600 turns in its primary and 1800 turns in its secondary. 450 V is obtained across its secondary. Then,
a) Which type of transformer is this?
b) What will be the voltage supplied across the primary?
Answer:
a) Step-up transformer
b) Step-up transformer
\(\frac{\mathrm{V}_{\mathrm{s}}}{\mathrm{~V}_{\mathrm{P}}}\) = \(\frac{\mathrm{N}_{\mathrm{s}}}{\mathrm{~N}_{\mathrm{p}}}\), so
V_P = \(\frac{\mathrm{V}_{\mathrm{S}} \times \mathrm{N}_{\mathrm{P}}}{\mathrm{~N}_{\mathrm{S}}}\) = \(\frac{450 \times 600}{1800}\) = 150 V
Voltage across primary = 150 V

Question 9.
When 0.1 A current is supplied to the primary of a transformer, 1 A current is obtained in the secondary.
a) Which type of transformer is this?
b) If 1000 V is supplied across the primary of this transformer, what will be its power?
c) What will be the power in the secondary?
d) What will be the voltage induced across the secondary?
Answer:
a) Type of transformer: Step-down transformer (secondary current > primary current)
b) Power in primary: P = V × I = 1000 × 0.1 = 100 W

c) Power in secondary: Approximately 100 W (In a transformer with no power loss (Ideal transformer), the power in the primary is equal to the power in the secondary.)

d) Voltage across secondary:
V_S = \(\frac{\mathrm{P}}{\mathrm{I}_{\mathrm{s}}}\) = \(\frac{1}{2}\)= 100 V

Question 10.
a) In a household electric circuit, to which device does the line coming from the electric pole reach first?
b) What is the key feature of the main switch?
c) What is the necessity of ELCB in a domestic electric circuit?
Answer:
a) The line from the electric pole reaches the watt- hour meter first.

b) Key feature of the main switch: It can cut off electricity to the whole house.

c) Necessity of ELCB: It protects people from electric shocks by detecting leakage current and disconnecting the supply.

Physics Class 10 Chapter 6 Notes Kerala Syllabus Electromagnetic Induction in Daily Life

Question 1.
What happens when a conductor is moved in a magnectic field?
Answer:
An electric current is produced.

Question 2.
What happens when a magnetic field is moved near a stationary conductor?
Answer:
An electric current is produced.

Question 3.
Based on the table answer the questions below.
a. What happens to the magnetic field lines associated with the conductor when the conductor and the magnet are in relative motion?
(a change in flux / no change in flux)
Answer:
Undergo a change in flux

b. Which are the situations where galvanometer needle deflected?
(when the magnetic flux associated with the conductor is changed / when there is no change in the magnetic flux associated with the conductor)
Answer:
The galvanometer needle deflected when the magnetic flux associated with the conductor is changed.

c. Why did the galvanometer needle deflect?
Answer:
Galvanometer needle deflects due to flow of electricity.

d. When did the direction of deflection of the galvanometer needle change?
Answer:
The direction of deflection of the galvanometer needle changed when the direction of motion of the magnet or solenoid was reversed, i.e., when the magnetic flux changed in the opposite way.

e. Why did the direction of deflection of the galvanometer needle change?
Answer:
The direction of deflection of the galvanometer needle changed because whenever the magnet or solenoid is moved the other way, the magnetic field through the coil changes in the opposite direction, so the needle moves the other way too.

Whenever the magnetic flux linked with a closed circuit changes, an emf is induced in the circuit. This phenomenon is electromagnetic induction.

The phenomenon of inducing an emf across a conductor due to a change in the magnetic flux linked with the conductor is electromagnetic induction.

• It is evident that when the direction of the change in magnetic flux is reversed, the direction of the induced emf also reverses.
• The emf (electromotive force) developed due to electromagnetic induction is the induced emf and the current thus produced is the induced current.
• It was Michael Faraday who discovered experimentally that electricity can be produced using a conductor and a magnetic field.

Repeating the previous experiment by making the following changes:

Experiment	Deflection of the galvanometer needle	Induced emf
	Increase / Decrease	Increase / Decrease
Using strong magnets	Increases	Increases
Using weak magnets	Decrease	Decrease
Number of turns of solenoid increased	Increases	Increases
Number of turns of solenoid decreased	Decrease	Decrease
Magnet/ Solenoid moves with greater speed	Increases	Increases
Magnet/ Solenoid moves with lesser speed	Decrease	Decrease

The induced current resulting from the induced emf caused the deflection of the galvanometer needle.

Activity	Deflection of the galvanometer needle (with respect to the previous experiment)
When the number of turns per unit length of a coil is increased	More
When the strength of the magnet is increased	More
When the speed is increased	More

Question 4.
Analysing table 6.2. write down methods to increase the emf and current?
Answer:
To increase the emf and current we should,

• Increase the number of turns per unit length of a coil
• Increase the strength of the magnet
• Increase the speed of movement of the magnet or the solenoid

Question 5.
Is there any difference between the current induced as a result of electromagnetic induction and the current obtained from a battery?
Answer:
Yes

Question 6.
The deflection of the galvanometer
(deflects to both sides / deflects in only one direction)
Answer:
The galvanometer needle deflects only in one direction. The direction of the flow of current does not change here.

Current that flows only in one direction is Direct Current (DC).

Question 7.
What change do you observe in the deflection of the galvanometer needle?
Answer:
The galvanometer needle deflects in both direction.

Question 8.
Is the induced current in the same direction?
Answer:
No, the induced current is not in the same direction, it changes direction.

Current that continuously changes direction at regular intervals of time is Alternating Current (AC).

Devices that operate on AC and DC currents are:

Operates on DC	Operates on AC
• Mobile phone • TV Remote • Laptop • Torch (flashlight)	• Mixie • Ceiling fan • Refrigerator • Air conditioner

Question 9.
Is it in the same manner that electricity is generated on a large scale? What arrangements are required to generate electricity on a large scale?
Answer:

• Powerful magnet
• Mechanism for movement
• Large coils of wire
• Energy source
• Transmission system
• Generator

Observe the figure 6.4.

Question 10.
What is its use?
Answer:
It is a device that produces electricity continuously by the movement of a magnet or coiled conductor, within a magnetic field.

Question 11.
What is the energy transformation that occurs here?

Answer:
Mechanical energy → Electrical energy

A generator is a device that converts mechanical energy into electric energy based on the principle of electromagnetic induction. Generators are of two types: • AC generator • DC generator

When a magnet is move towards an insulated coil or bringing an insulated coil towards a magnet, the work done which is the mechanical energy, which is converted into electrical energy.

Parts	AC Generator	DC Generator
NS	Field magnet	Field magnet
ABCD	Armature (coil)	Armature (coil)
B1, B2	Brushes	Brushes
R1, R2	Slip rings	Split ring

Question 12.
What happens to the magnetic field lines linked with the armature coil, when the armature of the generator rotates?
Answer:
When the armature rotates, the magnetic field lines linked with the coil changes continuously.

Question 13.
Will current be induced in the armature when there is change in flux?
Answer:
Yes, current will be induced in the armature when there is a change in magnetic flux.

Question 14.
Will there be a change in the direction of the current induced in the armature?
Answer:
Yes, the direction of the induced current in the armature changes after every half rotation.

Question 15.
Will the current induced in the armature be AC or DC?
Answer:
The current induced in the armature will be AC (Alternating current).

Question 16.
Which mechanism transfers the current induced in the armature to the external circuit?
AC generator: Slip rings, Brushes
DC generator: __________’ ____________
Answer:
Split rings, Brushes

Question 17.
What is the function of split rings in a DC generator?
Answer:
The function of split rings in a DC generator is to reverse the connection of the coil with the external circuit every half rotation(that is after every half rotation direction of current in armature coil reverses), so that the current in the external circuit flows in one direction only (making it DC).

Question 18.
Write down the similarities and differences between AC and DC generators.
Answer:
Similarities

• Works on the principle of electromagnetic induction
• Has a field magnet and an armature coil
• Uses brush to transfer current
• AC is induced in the armature of both generators.

Differences

AC Generator	DC Generator
• Current in the external circuit is alternating current • Uses slip rings	• Current in the external circuit is direct current • Uses split rings

Question 19.
What type of electricity will be obtained in the external circuit if the armature of a DC generator
is kept stationary and the field magnet is rotated? Why?
Answer:
If the field magnet is rotated and the armature is stationary, AC will be obtained, because the magnetic flux linked with the armature changes continuously.

Graphical Representation

Graphical representation of current obtained from AC generator, DC generator and cell

Question 20.
Is the electricity that reaches our homes produced by the same type of generators used in shops and other establishments?
Answer:
Yes, both use AC generators based on electromagnetic induction.

It is not practical to use small generators to produce the electricity needed for homes and big buildings. So, special centres called power stations are setup to generate electricity on a large scale. Power stations are named according to the type of energy used to run their generators.

The majority of the world’s electricity needs are met by the three types of power stations listed below.

Question 21.
By what name are the centres that produce electricity on a large scale using large generators known as?
Answer:
They are called Power stations.

Question 22.
Write down the energy transformation that takes place in each power station.

Answer:

Thermal power station	Heat energy → Electric energy
Nuclear power station	Nuclear energy → Electric energy
Hydroelectric power station	Potential energy (water) → Electric energy

There are power stations that generate electricity using wave energy, wind energy, solar energy, geothermal energy and tidal energy.

Question 23.
Find more information about such power stations, including their advantages and limitations, and present a seminar in class.
Answer:
An example is given below
Topic: Power Stations-advantages and limitations

Main points
There are different types of power stations used to generate electricity. Thermal power plants bum coal and produce a lot of energy but also cause air pollution. Hydro power plants use water from dams and are clean, but they need large rivers and big dams to work. Nuclear power plants create a large amount of electricity, but their waste is very dangerous. Solar power plants use sunlight, which is clean, but they only work during the day. Wind power plants use the wind to make electricity and are also clean, but only work when there is wind. Each type of power station has its own benefits and drawbacks.

Conclusion
Clean energy sources like solar, wind, and hydro are better for the environment. They do not pollute the air or produce harmful waste. To protect the Earth, we should use more renewable energy in the future.

Question 24.
Write down the similarities and differences between nuclear power station and thermal power station.
Answer:
Similarities

• Both produce electricity on a large scale.
• Both use steam to rotate turbines which drive generators.
• Both convert heat energy into electrical energy.
  Differences
• Thermal power station:
  • Heat is produced by burning coal, oil, or gas.
  • Causes more air pollution due to smoke and carbon dioxide.
  • Cheaper to build but costlier to run.
• Nuclear power station:
  • Heat is produced by nuclear fission of uranium or other fuels.
  • Produces radioactive waste instead of smoke.
  • Costly to build but cheaper to operate once set up.

Question 25.
Write down in order the energy transformations that occur in a hydroelectric power station.
Answer:
Potential energy of water → Kinetic energy → Mechanical energy (Turbine) → Electrical energy (Generator)

Question 26.
How does the electricity generated in power stations reach our houses?
Answer:
Electricity from power stations is sent through high- voltage transmission lines to substations, where the voltage is reduced. From there it travels through distribution lines and finally enters our homes at a safe voltage for use.

Observe the figures

The AC generated in power stations reach our homes through conducting wires.

Question 27.
Is there a possibility of energy loss when electricity is transmitted over long distances from power stations through conducting wires? Answer based on Joule’s Law.
Answer:
Yes, according to Joule’s Law, when current flows through wires, some electrical energy is lost as heat (H = I² Rt). Energy loss occurs during long distance transmission.

Question 28.
The energy loss primarily occurs in the form of heat. How can this be minimised?
Answer:
The energy loss can be minimised by:

1. Increasing the voltage of transmission (reduces current, I, so I² R loss decreases).
2. Using thicker wires or materials with low resistance.
3. Keeping transmission lines short wherever possible.

Question 29.
What are the three factors that influence the quantity of heat produced when current flows through a conductor?
Answer:

• Current (I)
• Time (t)
• Resistance of the conductor (R)

If the values of these factors are reduced, the quantity of heat produced can be reduced and thus energy loss can be minimised.

• It is not practical to reduce time.
• To reduce resistance, use materials with low resistivity.

Question 30.
Examine table 6.8 and answer the questions below.

Metal	Resistivity (Ωm)
Silver	1.59 × 10-8
Copper	1.68 × 10-8
Gold	2.44 × 10-8
Aluminium	2.65 × 10-8
Tungsten	5.60 × 10-8
Iron	9.71 × 10-8

a. Identify the metals with low resistivity?
Answer:

• Silver → 1.59 × 10^-8 Ωm
• Copper → 1.68 × 10^-8 Ωm
• Gold → 2.44 × 10^-8 Ωm
• Aluminium → 2.65 × 10^-8 Ωm

b. From these, find out the one with lowest cost and write down the most suitable metal?
Answer:
Among these lowest cost metal is Copper.

Reducing resistance beyond a certain limit is not practical. Current (I) is the third factor that needs to be reduced to minimise energy loss.

Question 31.
Can current be reduced?
Answer:
Yes.
We can reduce current by using higher voltage for the same power, higher voltage means less current, which lowers energy loss in the wires.

Question 32.
According to the formula P = VI, if the current (I) is reduced, what change occurs in the power (P)? (increases / decreases)
Answer:
Power (P) decreases

Question 33.
How can we reduce current without decreasing power?
(increase the voltage/ decrease the voltage)
Answer:
Increase the voltage

Question 34.
Write down the methods to minimise energy loss while transmitting electricity over long distances through conducting wires.
Answer:

1. Use suitable metal wires with low resistivity.
2. Increase voltage and decrease current without changing power.
3. Use thicker wires
4. Keep transmission lines short and direct where possible
5. Use efficient transformers
6. Regular maintenance of wires and connections

Question 35.
Which is the device that helps to increase voltage without change in power?
Answer:
Transformer

Question 36.
In which situations does the galvanometer needle deflect?
Answer:
The galvanometer needle deflects only when the switch is being turned on or turned off.

Question 37.
Is there a magnetic field around the coil when the switch is in the off position?
Answer:
No, a magnetic field is only there when electricity is flowing through the coil. When the switch is off, no electricity flows, so there is no magnetic field.

Question 38.
What about while turning on the switch?
Answer:
Yes, when you turn the switch on, a magnetic field is being created around the coil.

Question 39.
While turning on the switch, does the magnetic field linked with the second coil change?
Answer:
Yes, when the switch is turned on, the magnetic field linked with the second coil changes.

Question 40.
If so, will current be induced in the second coil due to electromagnetic induction?
Answer:
Yes, a current will be induced in the second coil due to electromagnetic induction

Question 41.
What methods can be adopted to induce current continuously in the second coil?
Answer:

1. Move a magnet or the second coil
2. Use AC current
3. Rotate the second coil

Conclusions:
The galvanometer deflects (momentarily) for the time when switch is turned On or off because there will be a change in magnetic field around the coil. There is no deflection when the switch remains in ON or off position. By moving a magnet or the second coil or by using AC current we can induce current continuously in the second coil.

Question 42.
To which coil of the transformer is AC supplied?
Answer:
Primary coil

Question 43.
In which coil is the AC induced?
Answer:
Secondary coil

Question 44.
What are the structural differences between stepup transformer and stepdown transformer?

Answer:

Stepup transformer	Stepdown transformer
• Thick wires are used in the primary	• Thin wires are used in the primary
• The primary has lesser number of turns than the secondary	• The secondary has less number of turns than the primary

Question 45.
How does a transformer change voltage?
Answer:
A transformer changes voltage by mutual induction.
In an ideal transformer, the induced emf per turn is equal in both coils.

Number of turns of coil in the primary (NP)	Voltage applied across primary coil (VP)	Voltage induced in one turn (e)	Number of turns of coils in the secondary (NS)	Induced voltage in the secondary (VS = NS × e )
100	100 V	1 V	100	100 × 1 V = 100 V
100	100 V	1 V	200	200 × 1 V = 200 V
200	100 V	0.5V	400	200 V
200	400 V	2 V	100	200 V
200	400 V	2 V	200	400 V

Question 46.
Analysing table 6.11, what conclusions can you arrive at?
Answer:
The ratio of the number of turns in the secondary to the primary in the transformer (\(\frac{N_s}{N_p}\)) will be the same as the ratio of the voltages across the secondary to the primary (\(\frac{V_s}{V_P}\)).
That is = \(\frac{V_s}{V_P}\) = \(\frac{N_s}{N_p}\)

Question 47.
A transformer with no power loss operating at 240 V AC supplies 12 V to an electric bell connected to it. Calculate the number of turns in the secondary, if the primary coil of the transformer has 4000 turns.
Answer:

Question 48.
A transformer with no power loss operating at an input voltage of 230 V has 120 turns in the secondary and 1200 turns in the primary. What is the output voltage of this transformer?
Answer:

In a transformer with no power loss (Ideal transformer), the power in the primary is equal to the power in the secondary.

Question 49.
When a transformer is used to change the AC voltage, does the current change?
Answer:
Yes. When a transformer changes the AC voltage, the current changes in the opposite way—if voltage increases current decreases, and if voltage decreases current increases.

An appliance connected to a stepdown transformer operating at 200 V consumes 1000 W of power. Suppose 100 V is obtained across its secondary.

Primary Power = Secondary Power
PP = 1000W	PS = 1000 W
VP × IP = 200 V × 5 A = 1000 W	VS × IS = 100 V × 10 A = 1000 W

Question 50.
Observe table 6.12 and write down the change that occurs in the current when the voltage decreases.
Answer:
When the voltage decreases, current increases.

Question 51.
What happens to the current, when the voltage increases?
Answer:
When the voltage increases, current decreases.

V_P I_P = V_S × I_S or = \(\frac{\mathbf{I}_{\mathbf{P}}}{\mathbf{I}_{\mathbf{S}}}\) = \(\frac{V_s}{V_p}\)
The secondary voltage of a stepup transformer will be higher than its primary voltage and the secondary current will be lower than its primary. The secondary voltage of a stepdown transformer will be lower than its primary voltage and secondary current will be higher.

Question 52.
In a transformer with no power loss (Ideal transformer), the primary has 3000 turns and the secondary has 150 turns. The primary voltage is 120 V and the current is 0.1 A. Calculate the secondary voltage and current.
Answer

Secondary voltage V_S = 6 V
Secondary current I_S = 2 A

Question 53.
Question 53.
Observe figure 6.12 and answer the questions below.
a) Discuss how electricity generated in a power station reaches houses and other establishments?
Answer:
Electricity is produced in a power station at about 11 kV.

A stepup transformer raises it to very high voltage (like 220 kV) for long-distance transmission through big power lines.

A stepdown transformer reduces it to 110 kV at substation and to 11 kV at secondary substation.

Finally smaller transformers reduce it further to 230 V and send it through local lines to houses and other buildings.

b. At what voltage is electricity generated in a power station?
Answer:
Electricity is generated at about 11 kV in a power station.

c. Which type of transformer is used in a power station?
Answer:
A stepup transformer is used in a power station to increase the generated voltage for long-distance transmission.

d. 11 kV electricity is generated in the power station.
To what voltage is it stepped up? (220 kV/ 110kV)
Answer:
It is stepped up to about 220 kV for long-distance transmission.

e. Where does the electricity reach after travelling through high voltage transmission lines?
Answer:
After travelling through high-voltage transmission lines, the electricity reaches substation .The voltage is reduced using step-down transformers in the secondary substation (1 lkV). This voltage is then reduced to the voltage required for distribution (230 V) using a distribution transformer.

f. Where are stepdown transformers used?
Answer:
The voltage from the transmission lines needs to be changed to a safe and usable voltage (230 V). To reduce high voltage (such as 11 kV, 110 kV or 220kV), stepdown transformers are used in substations (secondary substations, distribution substations) near homes and other establishments.

g. To what voltage is 11 kV AC reduced in a distribution transformer?
Answer:
230 V

h. What is the voltage of electricity supplied to houses?
Answer:
230 V

Question 54.
Observe figure 6.12, analyse the answers to the questions and prepare a short note on power transmission and distribution.
Answer:
1. Power Transmission:

• It is the process of transporting the electric power from power stations to substations near populated areas.
• Transmission uses the high voltage (e.g., 110 kV, 220 kV) to reduce current and minimize energy loss over long distances.
• Stepup transformers are used at the power stations to increase the voltage before transmission.

2. Power Distribution:

• It is the process of delivering electric power from substations to consumer’s premises (homes, offices, factories).
• Stepdown transformers reduce high voltage to safe, usable levels (230 V single-phase, 400 V three-phase).
• Ensures that the electricity has reached consumers efficiently and safely.

Question 55.
Explain the role of transformers in power transmission.
Answer:
1. Stepup Transformers (at Power Station):

• Increase the voltage from 11 kV (generated in the power station) to a high transmission voltages
  (e.g., 110 kV, 220 kV).
• Purpose: Higher voltage → lower current → reduces energy loss (heat) in transmission lines (P = I²R).

2. Step-down Transformers (at Substations):

• Reduce high transmission voltage to lower voltages that is suitable for consumer’s use (e.g., 230 V single-phase, 400 V three-phase).
• Purpose: Makes electricity safe and usable in house, offices, and industries.

The role of transformers in enabling efficient long-distance power transmission is very big. They can prevent excessive energy loss. They will make electricity safe for users.

Question 56.
What is the necessity of increasing the voltage of electricity generated at 11 kV in a power station?
Answer:
Electricity generated at 11 kV is stepped up to high voltage to reduce current and minimize energy loss during long-distance transmission.

Question 57.
What is the voltage used for domestic distribution?
Answer:
The voltage used for domestic distribution is 230 V AC (single-phase).

Question 58.
How does electricity reach the electrical appliances we use in our homes?
Answer:
Electricity reaches our home appliances through distribution wires after being stepped down to 230 V by a distribution transformer.

Question 59.
Observe the diagram of a household electric circuit and answer the questions below.

a. Where is the watt hour meter connected?
Answer:
It is placed at the beginning of the household electric circuit. The watt-hour meter is connected in series with the live (phase) wire and also to the neutral of the household supply.

b. How many wires reach the watt hour meter?
Answer:
Two wires

c. Which device is connected between the watt hour meter and the main switch?
Answer:
Main fuse

d. How is it connected? (in series / in parallel)
Answer:
In series

e. Where is the main switch placed?
Answer:
Main switch is placed right after the main fuse.

Main Switch
The main switch is a device used connect or disconnect the phase (live wire) and neutral line reaching the house hold circuit from the electric pole. The position of the main switch is right after the main fuse. Main switch is functioning as a double switch.

In addition, an ELCB (Earth Leakage Circuit Breaker) is connected to ensure more safety for the circuit. From there, the lines reach the MCB (Miniature Circuit Breaker) board and are distributed as branches to each part of the house.

• Appliances are connected across these lines in parallel.
• An appliance and the switch that controls it is connected in series to the phase line.
• When high power appliances are included in the circuit, they should be connected to the earth wire for better safety.
• For high power appliances, separate branch lines should be used with thick wires.
• Power plugs must be used to connect high power appliances.
• Red coloured wires are used commonly for the phase line, black for the neutral line and green for the earth line.

Question 60.
What are the situations that can cause excess current in a circuit?
Answer:
A short circuit occurs when the positive and negative terminals of a battery, or two wires in an AC main, come into contact with negligible resistance. This results in excessive current flow, which can lead to various hazards like fire.

Excess current and subsequent dangers can also arise in a circuit when a device with power more than the permissible limit, or many devices that consume excessive power, are connected. This type of excessive current flow in a circuit is overloading.

Question 61.
Why is it that a 2000 W induction cooker is not usually connected to a normal plug?
Answer:
A 2000 W induction cooker needs high current which can cause overload in a normal plug and cause heating that might damage the induction cooker and cause fire too.
A normal plug and its connected wires are designed to withstand a current of 5 A.

Question 62.
Will the current in a 2000 W induction cooker operating at 230 V be more or less than 5 A?
Answer:
According to the equation P = V × I
P = 2000 W
V = 230 V
Amperage = \(\frac{\text { Wattage }}{\text { Voltage }}\) = \(\frac{2000 \mathrm{~W}}{230 \mathrm{~V}}\) = 8.7 A

This means that more current than permissible limit will flow through the circuit. Connecting an appliance with higher power than permitted in a circuit in this manner is overloading. Therefore, connecting a high power appliance from a normal plug or using an extension cord to connect multiple devices, or using a multipin plug to connect more devices, will cause overloading.

Question 63.
Draw a circuit diagram for constructing a branch circuit with two bulbs, one three pin socket, one two pin socket, one fuse or MCB and necessary switches.
Answer:

Question 64.
What are the measures to be taken to protect household electrical appliances?
Answer:
Simple measures to protect household electrical appliances:

1. Use proper fuses or circuit breakers to prevent overloading.
2. Avoid wet hands or water contact while operating appliances.
3. Do not overload sockets or extension boards.
4. Switch off appliances when not in use.
5. Use voltage stabilizers for sensitive appliances.
6. Regularly check wiring and plugs for damage.
7. Keep appliances clean and dust-free.

Measures to ensure safety in domestic electricity distribution:
Safety fuse, ELCB (Earth Leakage Circuit Breaker), MCB (Miniature Circuit Breaker), three pin plug and earthing are commonly used safety measures in household electrical circuits.

1. Safety Fuse
Overloading, short circuits, lightning, etc., can cause excessive current flow through a circuit. A safety fuse is a device to protect living beings and equipment from the dangers caused by this.
It works based on the heating effect of electricity. The important part of a safety fuse is the fuse wire. Generally, alloys (eg: an alloy of tin and lead) are used to make fuse wire. Fuse wire has a relatively low melting point.

For each circuit, use a fuse wire that is appropriate for the current flowing through the circuit.

Question 65.
Which are the situations that could lead to excessive current causing the fuse wire to melt?
Answer:
Some situations that could lead to excessive current causing the fuse wire to melt are

• Connecting too many appliances at once
• Wires touching by mistake (short circuit)
• Bad wiring or damaged appliance
• Sudden high voltage

Question 66.
How is the fuse wire connected in the circuit?
(series / parallel)
Answer:
Series

2. MCB (Miniature Circuit Breaker)

MCB is a device used in branch circuits instead of safety fuse. When there is excessive current in a circuit due to short circuit or overload, the MCB automatically operates and disconnects the circuit ie., it trips. After resolving the circuit problem, the MCB switch can be turned on to restore the circuitto its original state. MCB works by utilising the magnetic effect and heating effect of electricity.

3. ELCB (Earth Leakage Circuit Breaker)

ELCB helps to disconnect the circuit automatically if there is current leak due to insulation failure or other reasons. This prevents electric shock to those who come in contact with the electric circuit or device. In household electric circuits, branch circuits start after the ELCB. Usually, one ELCB is sufficient for a household electric circuit. Subsequently, each branch starts with MCB.

4. Three Pin Plug and Earthing
The three pin plug is another device to ensure greater safety in household electric circuits.

Question 67.
Observe the figure and answer the questions below
a. Which line does the letter E indicate?
Answer:
Earth line

b. Where should this line be connected to the device?
Answer:
The earth line should be connected to the metal body of the device.

c. Where will the current flow, if a short circuit occurs in the device?
Answer:
The current will go safely to the earth through the earth wire.

d. Will this cause excess current flow?
Answer:
Yes. Excess current will flow to the earth if there is a fault.

e. If so, what will happen to the MCB/ safety fuse?
Answer:
The MCB or safety fuse will trip to stop the excess current and protect the device.

f. Observe the figure and analyse the answers. Then prepare a note on how the three pin plug ensures safety.
Answer:
In a three pin plug ,one of the three pins are connected to live, one to neutral and one to earth wire.

1. Live Wire: Carries current to the device.
2. Neutral Wire: Returns current to the supply.
3. Earth Wire: Connected to the metal body of the device. If a fault occurs, excess current flows through the earth wire.

The earth pin in a three-pin plug is longer and thicker, making it the first to make contact and the last to break when inserted into or pulled out of a socket. Its middle slit ensures a tight fit. The earth pin E makes contact with the earth line. The appliance’s body is attached to this pin. In the instance when the body makes any kind of electrical contact, the earth wire conducts electricity to the earth. Current is increased as it travels to the ground through a low resistance circuit. The circuit breaks as a result of the fuse wire’s increased generation of heat. This ensures both the instrument’s and the user’s safety.

RCCB (Residual Current Circuit Breaker)

Instead of ELCB, RCCB (Residual Current Circuit Breaker) is now used to ensure greater safety. It identifies current leaks by detecting, the difference between phase current and neutral current and then disconnects the circuit.

Question 68.
What will we do if we get an electric shock due to failure in safety system or carelessness?
Answer:
If someone gets an electric shock, switch off the main power immediately and take the person to a safe place. Then call for medical help.

Question 69.
What are the circumstances in which electric shock occur?
Answer:
Electric shock can occur when:

1. We touch a live wire.
2. There is faulty or damaged wiring.
3. Appliances are not earthed properly.
4. Water is near electricity.
5. Safety devices fail.

Question 70.
What dangers can people face due to electric shock?
Answer:
People can face these dangers due to electric shock:

1. Burns on the skin or inside the body.
2. Heart problems or irregular heartbeat.
3. Muscle injury or paralysis.
4. Death in severe cases.
5. Falls or accidents if shocked while standing on a height or near machines.

Safety must be ensured while working with electric circuits.

• If there is an electric shock, turn off the main switch immediately. Separate the person who gets an electric shock from the electric contact using an insulator.
• Under any circumstances do not touch with bare hands a person who received an electric shock.

Let’s look at the precautions to be taken to avoid electric shock. Precautions

• Do not handle electrical appliances or operate switches with wet hands.
• Plug into or unplug from a socket only after turning off the switch.
• Do not operate high power appliances in a normal socket.
• Do not touch the inside of a cable TV adapter. Ensure that the adapter has an insulator cover.
• Do not fly kites near power lines.
• Do not use iron/aluminium ladders, poles, etc., near electric lines.
• While carrying out repairs on household electric circuits, ensure that the main switch is turned off.
• During lightning, do not perform activities that involve contact with electric circuits (there is a possibility of excessive current in the circuit).
• Unplug appliances from sockets if there is a possibility of lightning.
• During rain and wind, transmission lines may touch the ground, creating the risk of accidents. If water enters houses (due to floods or other reasons), disconnect the power supply. After the water recedes, restore power only after the switch boards and the main switch are completely dry.

First Aid for Electric Shock
Provide first aid only after disconnecting the person who gets the shock from the electric wire.

• Rub the body to increase blood circulation and raise body temperature.
• Administer artificial respiration.
• Rub the muscles to restore them to their normal state.
• Start first aid to restart the heart perform chest compressions rhythmically and forcefully (Cardio Pulmonary Resuscitation). Take the person to the nearest hospital as soon as possible.

Std 10 Physics Chapter 6 Notes – Extended Activities

Question 1.
Open a three pin .top, understand how the wires are connected, and then connect wires in another three pin top in the same manner.
Answer:
Aim: To learn how wires are connected in a three-pin plug and safely replicate the connections.
Materials Required:
Three-pin plug (one for observing, one for connecting)
Screwdriver
Wires of an appliance

Procedure:

1. Open a three-pin plug carefully.
2. Observe how the live (red), neutral (black), and earth (green) wires are connected.
3. Note the positions of each wire: live to L, neutral to N, earth to E.
4. Connect the wires in the second plug in the same way.
5. Tighten screws and close the plug safely.

Conclusion: The experiment helps understand safe wiring of a three-pin plug and the role of each wire in protecting users and appliances.

Question 2.
Which are the types of power stations used to generate electricity in countries worldwide, including India?
Calculate the percentage of electricity generated by each category in the total power production and prepare a table in the descending order of their percentage of production. ,
Answer:
An example is given below

Types of Power Stations

1. Thermal Power Stations
   Coal-based
   Gas-based
   Oil-based
2. Hydroelectric Power Stations
3. Nuclear Power Stations
4. Solar Power Plants
5. Windmills
6. Biomass Power Plants

Global Electricity Generation (mention a particular year for which study is conducted)

Source	Percentage (%)
Coal	34%
Natural Gas	22%
Hydropower	16%
Wind & Solar	13%
Nuclear	9%
Other Renewables	3%
Oil	2%
Total	100%

India’s Electricity Generation (mention a particular year for which study is conducted)

Source	Percentage (%)
Coal	73%
Hydropower	9%
Solar	8%
Wind	5%
Nuclear	3%
Biomass	2%
Gas & Oil	1%
Total	100%

(The table shows indicative values, original values may vary)
Coal remains the dominant source of electricity generation globally and in India.Renewable sources (wind, solar, hydro) are growing rapidly but still contribute a smaller share compared to fossil fuels.

Question 3.
Construct and demonstrate a branch circuit including two electric bulbs, a three pin socket, a two pin socket, a fuse or MCB, electric bulbs operated by a two way switch and switches required for that. (This activity should be done only under adult supervision).
Answer:
Hint
Aim: To construct and understand a household branch circuit with bulbs, sockets, switches, and protection devices.

Materials Required: 2 electric bulbs with holders, 3-pin socket, 2-pin socket, Fuse or MCB, Two-way switch, Single-pole switches, Connecting wires, Screwdriver, insulating tape

Procedure:

1. Connect the main supply to a fuse or MCB for protection.
2. From the MCB, connect wires to the three-pin socket and two-pin socket.
3. Connect the two bulbs in the circuit so that they can be operated by two-way and single-pole switches.
4. Use proper live (red), neutral (black), and earth (green) connections.
5. Test the circuit carefully with adult supervision. Conclusion: The activity demonstrates how a branch circuit works in homes, how switches control bulbs, how sockets are connected, and how a fuse or MCB protects against overcurrent.

This setup helps understand safe wiring and control of electricity in a household.

Electromagnetic Induction in Daily Life Class 10 Notes

Electromagnetic Induction in Daily Life Notes Pdf

• Whenever the magnetic flux linked with a closed circuit changes, an emf is induced in the circuit. This phenomenon is electromagnetic induction.
• The phenomenon of inducing an emf across a conductor due to a change in the magnetic flux linked with the conductor is electromagnetic induction.
• The emf (electromotive force) developed due to electromagnetic induction is the induced emf and the current thus produced is the induced current.
• To increase the emf and current we should,
  • Increase the number of turns per unit length of a coil
  • Increase the strength of the magnet
  • Increase the speed of movement of the magnet or the solenoid
• Current that flows only in one direction is Direct Current (DC).
• Current that continuously changes direction at regular intervals of time is Alternating Current (AC).
• A generator is a device that converts mechanical energy into electric energy based on the principle of electromagnetic induction. Generators are of two types:
  • AC generator
  • DC generator
• Steps to minimise energy loss while transmitting electricity over long distances through conducting wires.
  • Use suitable metal wires with low resistivity.
  • Increase voltage and decrease current without changing power.
  • Use thicker wires
  • Keep transmission lines short and direct where possible
  • Use efficient transformers
  • Regular maintenance of wires and connections
• Transformer is a device that works on the principle of mutual induction. Transformers change AC voltage without change in power.
  Transformers are of two types.
  1. Stepup transformer: transformers that increases the AC voltage
  2. Stepdown transformer: transformers that decreases the AC voltage
• The ratio of the number of turns in the secondary to the primary in the transformer (\(\frac{N_S}{N_P}\)) will be the same as the ratio of the voltages across the secondary to the primary (\(\frac{V_S}{V_P}\))
  That is \(\frac{V_S}{V_P}\) = \(\frac{N_S}{N_P}\)
• In a transformer with no power loss (Ideal transformer), the power in the primary is equal to the power in the secondary.
• V_P × I_P =V_S × I_S or \(\frac{I_P}{I_S}\) = \(\frac{V_S}{V_P}\)
• The secondary voltage of a stepup transformer will be higher than its primary voltage and the secondary current will be lower than its primary. The secondary voltage of a stepdown transformer will be lower than its primary voltage and secondary current will be higher.
• Measures to ensure safety in domestic electricity distribution: Safety fuse, ELCB (Earth Leakage Circuit Breaker), MCB (Miniature Circuit Breaker), three pin plug and earthing are commonly used safety measures in household electrical circuits.
• Electric shock is the impact caused by the flow of current through the body.

INTRODUCTION

One basic energy source that is necessary for modern living is electricity. Our communication systems, schools, hospitals, businesses, and houses are all powered by it. Many resources, including coal, water, wind, sunlight, and nuclear energy, can be used to produce electricity. Michael Faraday’s discovery of electromagnetic induction was one of the most significant in the history of electricity. Generators in power plants use this idea to create energy. Additionally, it is utilized in gadgets like wireless chargers, transformers, and induction cookers. Conductors, such as copper wires, carry electricity, which can be controlled with switches and circuits. Electricity must be handled and used properly to prevent accidents and shocks and also to conserve energy. This chapter explores topics like electromagnetic induction, alternating and direct current generator, transformer, power transmission and distribution, household electrification and electric shock.

Electromagnetic Induction
• Electromagnetic induction is the process of producing electricity from motion. An electric current is created in the wire when a magnet moves near a coil of wire, or when the coil moves near a magnet. This happens because of the movement of magnet changes the magnetic field around the coil, which makes the electrons in the wire start to flow.

• This idea was discovered by Michael Faraday and is one of the most important principles in science. It is used in generators to produce electricity in power stations, in transformers to change voltage, in bicycle dynamos, induction stoves, and even in wireless chargers. Without electromagnetic induction, we would not have the easy and powerful supply of electricity that we enjoy today.

Alternating current (AC), Direct Current (DC)
• Electricity flows in two main ways: Alternating Current (AC) and Direct Current (DC).

• Direct Current (DC):
In DC, the electric current flows in one constant direction. It is steady and does not change with time. Batteries, solar cells, and mobile phone chargers give DC.
DC is used in gadgets and electronics

• Alternating Current (AC):
In AC, the electric current changes direction back and forth many times every second. This type of electricity is used in homes and industries because it is easier to send over long distances. The electricity we get from power stations is AC.
AC powers our homes, schools, and cities.

Generator
• A generator is a device that produces electricity. It works on the principle of electromagnetic induction, discovered by Michael Faraday. When a coil of wire is made to rotate inside a magnetic field (or when a magnet rotates near a coil), it creates an electric current.

• Generators are used in power stations to produce the electricity that we are using at our home, in schools, and in factories. They are also found in bicycles (dynamos), cars, and backup power systems. In simple words, a generator changes the mechanical energy (movement) into electrical energy, helping to light up our world and run our machines we use in our day to day life.

Transformer
• A transformer is a device that is used to increase or decrease the voltage of electricity without changing the amount of power. It works on the principle of mutual induction. A transformer has two sets of coils which are primary and secondary coils wrapped around an iron core. When alternating current (AC) flows through the primary coil, it creates a magnetic field that induces a Voltage in secondary coil.

• Transformers have very importance with electricity. In the power stations, stepup transformers used to increase the voltage so that electricity can travel long distances with less energy loss. Near our home, stepdown transformers are used to reduce the voltage to a safe level for household use. In simple words, a transformer helps electricity to move safely and efficiently from the power plants to our homes and workplaces.

Power transmission and distribution
• Power transmission and distribution is the process of carrying the electricity from the power stations to our home, schools, and factories. After electricity is generated in a power plant, it travels to a long distances to reach people safely and efficiently.

• At first stepup transformers will increase the voltage so that the electricity can move through high-voltage transmission lines with less energy loss. Next step is that when it reaches cities or towns, stepdown transformers which lowers the voltage to safer levels. Finally the electricity can pass through distribution lines and enters our homes at the right voltage for everyday use.

Household wiring

• Household wiring is the system of electrical wires and connections that brings the electricity safely into our homes. It carries the electric current from the main supply to lights, fans, sockets, and other appliances we use in our day to day life.
• In a house wiring system, three main wires we used are:
  • Live (Phase) wire – which carries the current from the supply.
  • Neutral wire which completes the circuit back to the supply.
  • Earth wire – which provides safety by directing excess current into the ground in case of a fault.
• Important safety devices like fuses, MCBs (Miniature Circuit Breakers), and switches are included so that to protect against overload and short circuits. So we can say that household wiring is like the road network of electricity which brings power to every room safely and efficiently.

Electric Shock

• An electric shock happens when the electricity is passed through the human body. Our body can conduct the electricity because it contains water and salts. When someone touches a live wire or faulty appliance, the electric current flows through their body and then to the ground. This can cause pain, burns, muscle cramps, or even serious injury and death to the affected person.
• Electric shocks can be prevented by:
  • Using insulated wires and proper household wiring.
  • Installing earthing and fuses/MCBs for safety.
  • Avoiding wet hands while handling electrical devices.
• In simple words, an electric shock is the harmful effect of electricity on our body. By the careful use of electrical appliances we can keep us safe and protected.

There are various types of electromagnets are used for different purposes. Some of them are given below.

• Electric crane
• Electric motors
• Electric bell
• Electric rails
• Electric fan
• Loud speakers

In all these, electric energy is converted into magnetic energy. A magnet can be made using electricity by making an electromagnet by winding insulated copper wire over a soft iron core and passing electricity through the wire. . From this idea, Michael Faraday developed the principle of electromagnetic induction, which later led to the invention of the generator.

ELECTROMAGNETIC INDUCTION
A current carrying conductor placed in a magnetic field experiences a force and develops a tendency to move.

ACTIVITY
Arrange a magnet, a conductor in the shape of a solenoid and a galvanometer as shown in the figure.

Observation

a) ACTIVITY 1
Connect a 1.5 V cell, a 470 Ω resistor, a switch and a galvanometer in series. Turn on the switch.

b) ACTIVITY 2
Repeat the activity with the magnet and coil. Move the solenoid connected to the galvanometer rapidly towards and away from the magnet. Observe the galvanometer needle.

TRANSFORMER
These are different types of transformers.

ACTIVITY 1
Aim: To understand how transformers work.
Materials required: • PVC pipe -1 [12 cm long with 4 cm (1.5″) diameter]

• PVC pipe – 1 [12 cm long with a 2.5 cm (1″) diameter)
• Insulated copper wire-28 gauge (250 g)
• 9 V DC and 9 V AC source
• Galvanometer
• Soft iron

Procedure:
Wind approximately 600 turns of insulated copper wire around each PVC pipe.

Connect a 9 V DC source and a switch to the ends of the first coil. Connect a galvanometer between the ends of the second coil. Arrange them as close as possible, without touching each other.

Observation:

Activity	Galvanometer needle Deflects / does not deflects
The switch is turned on	Deflects
The switch is in the on position	Does not deflects
The switch is turned off	Deflects
The switch is in the off position	Does not deflects

ACTIVITY 2
Observation :

Activity	Galvanometer needle Deflects / does not deflects
The switch is turned on	Deflects
The switch is in the on position	Deflects
The switch is turned off	Deflects
The switch is in the off position	Does not deflect

Conclusion: The galvanometer deflects whenever the circuit is complete (i.e., when the switch is on). This is because the AC current is constantly changing, which creates a constantly changing magnetic field that induces a current in the second coil. When the switch remains in off position no current flows, so there is no magnetic field and thus no induction. (There is a momentary deflection for the time when switch is turned off).

Consider two coils kept close to each other. When the intensity or direction of current in one of them changes, the magnetic field around it changes. As a result, an emf is induced in the second coil. This phenomenon is mutual induction.

ACTIVITY 3
Repeat the activity by inserting the smaller coil inside the larger coil.

Observations: The galvanometer needle will deflect more strongly.

Conclusion: By inserting the smaller coil inside the larger one, the magnetic field from the larger coil is more concentrated within the smaller coil. This results in a greater change in magnetic flux, which in turn induces a stronger current in the second coil.

ACTIVITY 4
Repeat the activity by inserting a soft iron core inside the smaller coil.

Observation: The galvanometer needle will deflect much more strongly.

Conclusion: A soft iron core acts as a concentrator for the magnetic field lines. When you place it inside the coil, it greatly increases the strength of the magnetic field. This stronger magnetic field leads to a larger change in magnetic flux, which induces a much greater current in the second coil. This is why a soft iron core is used in devices like transformers to maximize the induced current.
Transformer is a device that works on the principle of mutual induction. Transformers change AC voltage without change in power. Transformers are of two types.
1. Stepup transformer
2. Stepdown transformer
i) Stepup transformer: transformers that increases the AC voltage
ii) Stepdown transformer: transformers that decreases the AC voltage

ELECTRIC SHOK
Electric shock is the impact caused by the flow of current through the body.

CARDIO PULMONARY RESUSCITATION (CPR)

The letters C-A-B are used to remember the sequence for performing the steps of CPR.
C-Compressions
A-Airway
B-Breathing

Compressions: Restore Blood Flow (Chest Compressions)
Compression refers to pressing firmly and quickly on the person’s chest in a specific rhythm using your hands. Compressions are the most crucial step in CPR. To perform CPR compressions, follow the steps below:

1. Lay the person flat on a firm surface.
2. Place the palm of one of your hands at the centre of the person’s chest.
3. Place your other hand on top of your first hand. Your elbows should be straight and your shoulders should be directly above your hands.
4. Press down on the chest by at least 2 inches (under no circumstances, should it exceed 2.4 inches). While compressing the chest, use not just your hands, but your body weight as well.
5. Press hard and fast at the centre of the chest. Try to perform 30 compressions in 15-20 seconds. Allow the chest to fully return to its original position after each compression.
6. If you are not trained in CPR, continue chest compressions until there are signs of movement or emergency medical help arrives. If you are trained in CPR, begin rescue breaths.

Open the Airway
After 30 chest compressions, perform the following to open the person’s airway. This action is called the Head – Tilt, Chin – Lift.

1. Place the palm of your hand on the person’s forehead.
2. Gently tilt the head backward.
3. With your other hand, gently lift the chin to open the airway.

Rescue Breathing
After opening the airway using the Head-Tilt, Chin-Lift method, do the following.

1. For mouth to mouth breathing, close the person’s nose and cover their mouth with your mouth (you can place a handkerchief with a hole in the middle, between the mouths).
2. Give the first rescue breath. This should last one second-observe if the chest rises.
3. If the chest rises, give another breath. If the chest does not rise, perform the Head- Tilt, Chin-Lift again and give a breath.

After thirty chest compressions, give two breaths. This action is considered one cycle. Repeat this cycle until there are signs of movement or emergency medical help arrives.

The comprehensive approach in SCERT Kerala Syllabus 10th Standard Physics Textbook Solutions and Class 10 Physics Chapter 5 Electric Energy: Consumption and Conservation Notes Questions and Answers English Medium ensure conceptual clarity.

SSLC Physics Chapter 5 Notes Questions and Answers Pdf Electric Energy: Consumption and Conservation

SCERT Class 10 Physics Chapter 5 Electric Energy: Consumption and Conservation Notes Pdf

SSLC Physics Chapter 5 Questions and Answers – Let’s Assess

Question 1.
An electric heater operating at 230 V draws 2 A current.
a) What is the resistance of the heater?
b) Calculate the heat produced when this heater operates for 10 minutes.
c) What is the power of this appliance?
Answer:
V = 230 V, I = 2A, t = 10 × 60 s
a) R = \(\frac{V}{I}\) = \(\frac{230}{2}\) = 115 Ω

b) H = VIt
H = 230 × 2 × 600
= 276000 J

c) H = Pt
p = \(\frac{276000}{600}\) = 460 W

Question 2.
a) A heating appliance operating at 230 V supply consumes 2 A current. What is the quantity of heat produced in five minutes?
b) What is the energy consumed by this appliance in five minutes while operating at 115 V?
Answer:
a) V = 230 V, I = 2 A, t = 5 × 60 = 300 s
H = 230 × 2 × 300
= 138000J

b) V = 1115 V
R = \(\frac{230}{2}\) = 115 Ω
I = \(\frac{V}{R}\) = \(\frac{115}{115}\) = 1A
H = 115 × 1 × 300
= 34500 J

Question 3.
In a house, a 500 W electric iron operates for one hour, two 40 W fans for 8 hours, and five 12 W LED bulbs for 10 hours. Calculate in unit the energy consumption per day in that house.
The tariff of electricity for domestic consumers in Kerala is given below (subject to change).

Answer:
Electric energy (in kilo watt hour)
= \(\frac{\text { Power in watt } x \text { time in hour }}{1000}\)
Energy consumed by electric iron (in kWh)
= \(\frac{500 \times 1}{1000}\) = 0.5 kWh = 0.5 unit
Energy consumed by fan (in kWh)
= \(\frac{2 \times 40 \times 8}{1000}\) = 0.64 kWh = 0.64 unit
Energy consumed by LED bulb (in kWh)
= \(\frac{5 \times 12 \times 10}{1000}\) = 0.6 kWh = 0.6 unit
Total energy consumption in a day = 0.5 + 0.64 + 0.6 = 1.74 kWh
Total energy consumption in a day in units =1.74 unit

Question 4.
In a house, a 600 W grinder operates for one hour, three 60 W fans for six hours, and ten 10 W LED bulbs for 10 hours daily.
a) What will be the electric energy consumed in units per month?
b) If the appliances operate in the same way, calculate the electricity bill for two months in that house.
(Use the tariff given in table 5.8)
The tariff of electricity for domestic consumers in Kerala is given below (subject to change).

Answer:
a) Energy consumed by grinder
= \(\frac{600 \times 1}{1000}\) = 0.6 kWh = 0.6 unit
Energy consumed by fans
= \(\frac{3 \times 60 \times 6}{1000}\) = 1.08 kWh = 1.08 unit
Energy consumed by bulbs
= \(\frac{10 \times 10 \times 10}{1000}\) = 1 kWh = 1 unit
Total energy consumption in a day
= 0.6 + 1.08 + 1 = 2.68 kWh
= 2.68 unit
Total energy consumption in a month (30 days) = 80.4 units

b) Total energy consumption in for two months (60 days) = 80.4 × 2 = 160.8 units
For up to 250 units of energy consumption it is known as Telescopic and above that it is non telescopic.
For 2 months the energy consumed is 160.8 units. Here the energy consumption comes under the telescopic section.

Check for the energy consumption charge for each range of unit.
For first 50 units of the total consumption ,the charge = unit × energy charge per unit = 50 × 3.35 = 167.5
For the second 50 units of the total consumption,
the charge = 50 × 4.25 = 212.5
For the third 50 units of the total consumption,
the charge = 50 × 5.35 = 267.5
For the remaining 10.8 .units the total
consumption charge = 10.8 × 7.2 = 77.76

So the total consumption charge = Rs. 725.26 The charge for the single phase (usually for household connections) for a month lies in the electricity consumption range of 50-100, is also added up with this to give the total electricity bill.

Total electricity bill = 725.26 + (85 × 2) = 725.26 + 170 = Rs. 895.26 (other charges may also add up to the bill you receive. In the given bill only energy charge per unit and single phase fixed charge is added up based on the tariff | given in table 5.8)

Question 5.
Two heaters A and B operate at 230 V. Heater A draws 2 A current and heater B draws 2.5 A current.

a) Calculate the power of the heaters in figure 5.12 (a) and (b).
b) Which heater has higher resistance?
c) If both heaters operate for 5 minutes each, which heater will produce more heat?
Answer:
a) Power, P = VI
For heater A
V = 230 V, I = 2A
P = 230 × 2 = 460 W
For heater B
V = 230 V, I = 2.5 A
P = 230 × 2.5 = 575 W

b) Resistance of heater A, R = \(\frac{V}{I}\) = \(\frac{230}{2}\) = 115 Ω
Resistance of heater B, R = \(\frac{V}{I}\) = \(\frac{230}{2.5}\) = 92 Ω
Heater A has more resistance

c) H =VIt
t = 5 × 60 = 300 s
For heater A, H = 230 × 2 × 300 = 138000 J
For heater B, H = 230 × 2.5 × 300 = 172500 J
Heater B produces more heat.
When the time of operation is same, the heater with more power produces more heat.

Question 6.
Which of the given statements is correct with regard to the heating element?

(a) Low melting point
(b) High resistivity
(c) Ability to remain in red hot state
(d) Low oxidation resistance
(e) High melting point
(f) High oxidation resistance
i. abfc
ii. abfe
iii. bdfe
iv. beef
Answer:
iv. bcef

Question 7.
Two bulbs, 230 V, 40 W and 230 V, 60 W are arranged as shown in the figures.

If 230 V is applied, which bulb will be brighter in each circuit?
Answer:
For 40 W bulb, R = \(\frac{V^2}{P}\) = \(\frac{230^2}{40}\) = 1322.5 Ω
For 60 W bulb, R = \(\frac{V^2}{P}\) = \(\frac{230^2}{60}\) = 881.7 Ω
40 W has higher resistance than 60 W.

In the parallel circuit (5.13(a)), the voltage across both bulbs is the same (equal to the source voltage, 230 V). The power dissipated by each bulb is given by P = \(\frac{V^2}{R}\). Since the voltage is the same, the bulb with lower resistance will dissipate more power and thus be brighter. Since resistance of 60 W bulb is lesser than resistance of 40 W bulb, the 60 W bulb will be brighter in the parallel circuit.

In the series circuit (5.13(b)), the current flowing through both bulbs is the same. The power dissipated by each bulb is given by P = VI = (IR)I = I²R. Since the current I is the same, the bulb with higher resistance will dissipate more power and thus be brighter. Since resistance of 40 W bulb is higher than resistance of 60 W bulb, 40 W bulb will be brighter in the series circuit.

In general, in a parallel connection, device of higher power will have lower resistance ,it will draw more current, produce more heat and glow brighter and in a series connection, device of lower power will have higher resistance, it will share more voltage and glow brighter.

Question 8.
To reduce electricity consumption in our houses, we can maximise the use of sunlight dining the day. Do you agree with this statement? Explain how.
Answer:
Yes, I agree with the statement.
I do believe that utilising sunlight during the day lowers the amount of electricity used. One free and natural light source that we may use in our home is sunlight. By opening the windows and drapes ,rooms can be made brighter without the use of artificial lighting. Our electricity costs are reduced as a result. To maximize daylight, we should choose locations for work or study next to windows. Mirrors and light-colored walls can improve the room’s ability to reflect sunlight. When we rely upon natural light, it reduces the reliability on electricity from power plants, thus contributing to pollution reduction. Using sunlight to save electricity at home is easy and environmentally beneficial.

Question 9.
In the context of the energy crisis, write down any two suggestions that can be implemented to reduce energy consumption in newly constructed houses.
Answer:

• New houses should have large windows to use sunlight and fresh air instead of lights and fans.
• Solar panels can be installed to produce electricity and lower electricity bills.
• Energy-saving appliances like LED lights and 5-star rated appliances should be used.
• Good insulation in walls and roofs can keep the house cool or warm without using much electricity.

Question 10.
What is the necessity for reducing carbon footprint?
Answer:
Both direct and indirect emissions of greenhouse gases come from people, families, businesses, events, services, and goods. The amount of greenhouse gases that are released, transformed, expressed as equivalent to the measure of carbon dioxide, is carbon footprint.

Reducing the carbon footprint is important because it helps slow down climate change by lowering greenhouse gas emissions. In turn, this reduces the occurrence of severe weather phenomena like droughts and floods. Preserving natural habitats for plants and animals and limiting pollution are two further ways in which it protects the environment. Decreased emissions lead to cleaner air and water, which enhances public health by lowering respiratory and other illnesses. By conserving limited natural resources like fossil fuels, more efficient energy use promotes sustainability. We contribute to a safer and better Earth for coming generations by reducing carbon emissions.

Physics Class 10 Chapter 5 Notes Kerala Syllabus Electric Energy: Consumption and Conservation

Question 1.
Which are the appliances in houses that operate using electricity?

Answer:

• Tube light
• Electric kettle
• Fan
• Electric iron
• Induction cooker
• Electric drill machine
• Refrigerator

Different electrical appliances are used for different purposes. These appliances convert electric energy into different forms of energy.

Question 2.
What forms of energy are produced when a mixie operates? Write them down.
Answer:

• Mechanical energy
• Sound energy
• Heat energy

The electric energy we supplied is transformed into various forms when the mixie is operated. Effect of electric current-The useful form of energy into which an appliance mainly converts electric energy is considered the effect of electric current in that appliance.

Question 3.
Observe the appliances in figure 5.1 and the appliances already listed. Based on their function, identify the effect of electric current utilised in each and complete table 5.1 given below.

Answer:

Name of the appliance	Function	Energy conversion	Effect of electric current
Electric kettle	Heats water	Electric energy → heat energy	Heating effect
Mixie	Grind or mix ingredients	Electrical energy → mechanical energy	Mechanical effect
Electric iron	To iron clothes	Electric energy → heat energy	Heating effect
Tube light	Provides light	Electric energy → Light energy	Lighting effect

Question 4.
From the table, you may have understood that electric current can produce various effects. Which of these appliances produce heat?
Answer:

• Electric iron
• Electric kettle

Question 5.
Connect a 5 cm long nichrome wire to a 9 V battery as shown in Figure 5.2.

Switch on and observe the nichrome wire.
What change do you notice?
Answer:
When current passes through the nichrome wire, heat energy is produced.

The process of production of heat, when electricity flows through a conductor is Joule heating or Ohmic heating. The part used to produce heat energy in heating appliances is the heating element.

Observe the pictures of the given electric heating appliances.

You may have noticed that the part common to all these appliances is the heating coil (heating element).
The heating coil is made of an alloy, nichrome.
(There are also heating appliances which does not make use of heated coils. Microwave ovens and
induction cookers are a few examples.)

Question 6.
What are the characteristics of nichrome that make it suitable for a heating element?
Answer:

• High oxidation resistance (oxidation resistance is the ability of a material to resist corrosion due to contact with oxygen or other oxidisers at high temperature).
• Ability to provide heat energy for a long time in a red hot state.
• High resistivity (due to this property even a nichrome wire of short length can provide sufficient resistance)
• High melting point(due to this property, nichrome is able to tolerate the high temperatures needed
  for efficient heating without melting or deforming.)

We know that all materials do not conduct electricity in the same way.

Resistivity is one of the intrinsic properties of a material that mainly determines the resistance which is the characteristic of a conductor. Resistivity is different for each material.

Resistivity and conductivity.
The resistance of a conductor with an area of cross section of one square metre and a length of one metre is the resistivity of the material of the conductor. It is denoted by the Greek letter ρ(rho). Its unit is ohmmetre (Ωm). Conductivity is the ability of a material to conduct electricity. This is the reciprocal of resistivity.

The factors which influence the resistance of a conductor are length of the conductor
(l), area of cross section (A) and the nature of the material (ρ). The relation of resistance (R) with these factors is given by the equation R = \(\frac{\rho l}{A}\)

Activity to find out the factors that influence the heat produced in a conductor carrying current.
• Construct a circuit which consists of a 5 cm long nichrome wire, 6 V battery eliminator, etc., as shown in figure 5.4. Take 20 mL of water in a boiling tube. Immerse the nichrome wire and a thermometer into it. Adjust the rheostat to vary the current. Record the temperature in table 5.2 every two minutes. Repeat the experiment by replacing the water in the boiling tube each time.

Observation
Temperature of water before starting the experiment = 31°C

Current (A)	Temperature (°C)
0.5	33
1	35
1.5	37

Analysis
On analysing table 5.2 given above we can understand that the temperature of water increases with increase in current. In this experiment a fixed quantity of water (20 mL) is heated by passing current. To increase the temperature of a fixed quantity of water more heat is required. Hence as the quantity of heat received by the water increases, the temperature also increases. Therefore, it is understood that when the current increases heat produced also increases.

• Adjust the rheostat to make the current 1 A. In table 5.3 given below record the temperature of water, every 2 minutes.
Observation

Time (in minutes)	Temperature (°C)
0	31
2	33
4	35
6	32

Analysis
Temperature increases because the current flowed for a longer time. We can understand that the heat produced increases as the time of flow of current increases.

Activity
Take nichrome wire and aluminium wire of equal length (5 cm) and equal area of cross section. Using them make a circuit as shown in the figure.

Pass current through the circuit for about 2 minutes using a 9 V, 50 W eliminator. Place a thin paper on both aluminium and nichrome wire.

Question 7.
What do you observe?
Answer:
Because the nichrome wire generates a lot more heat than the aluminium wire, we can see that the thin paper on the nichrome wire is likely to bum or char while the paper on the aluminium wire would either stay the same or only warm slightly.

Question 8.
Which conductor becomes hotter?
Answer:
Nichrome wire becomes hotter.

Question 9.
The magnitude of current in the nichrome wire and aluminium wire is (the same / different).
Answer:
Same

Question 10.
The resistance of nichrome wire and aluminium wire is (the same/different).
Answer:
Different
The nichrome wire become hotter because its resistance is greater than that of the aluminium wire. Resistance is another factor that influences the quantity of heat produced in a conductor carrying current.

Question 11.
From the experiments conducted, note down the three factors that influence the quantity of heat produced in a current carrying conductor:
Answer:

• Current (I)
• Resistance of the conductor(R)
• Time for which current flows(t)

The scientist James Prescott Joule discovered the relation between the heat produced in an electric conductor and the factors influencing the quantity of heat.

Joule’s law
The quantity of heat produced in a current carrying conductor is directly proportional to the square of the current (I²), the resistance of the conductor (R) and the time (t) for which the current flows. This is Joule’s law. If a current I flows through a conductor having resistance R for a time t, according to Joule’s law, the quantity of heat produced will be H = I²Rt. Its SI unit is joule (J).

Question 12.
A current of 0.5 A flows through a conductor with 100 Ω resistance for 5 minutes.
a) What will be the quantity of heat produced?
b) If a current of 1A flows through this conductor for 5 minutes, what will be the quantity of heat produced?
Ans:
a) R = 100 Ω
I = 0.5 A
t = 5 × 60s
H = ?
H = I²Rt
= 0.5 × 0.5 × 100 × 5 × 60 J
= 7500 J

b) I = 1A, H = I²Rt
H = 1 × 1 × 100 × 5 × 60 J
= 30000J

Question 13.
When the current was doubled, the heat produced in the conductor became 4 times. If so, what happens to the heat produced if the current is halved?
(halved/ quartered)
Answer:
quartered
The electrical appliances commonly used in houses operating at 230 V.

Other forms of Joule’s Law
We can formulate other equations to calculate the quantity of heat.
According to ohm’s law
V = IR
Hence I = \(\frac{V}{R}\)
On substituting the value of I in the equation
H = I²Rt
H = (\(\frac{V}{R}\))² Rt
So, we get H = \(\frac{V^2 t}{R}\)
Similarly, if we substitute R = \(\frac{V}{I}\) in the equation
H = I²Rt
We get H = VIt
H = I²Rt = \(\frac{V^2 t}{R}\) = VIt

Question 14.
If the resistance of a heating appliance operating at 230 V is 920 Ω , what is the quantity of heat produced in 10 minutes?
Answer:
V = 230 V, R = 920 Ω, t = 10 × 60 s
H = \(\frac{V^2 t}{R}\)
= \(\frac{230 \times 230}{920}\) × 10 × 60 = 34500 J

Question 15.
If 7500 J of heat is produced in 30 s in a conductor having 2500 resistance, what is the current through the conductor?
Answer:
H = 7500 J,
t = 30 s,
R = 250 Ω
H = I²Rt
\(\frac{H}{R t}\) = I²
I = \(\sqrt{\frac{H}{R t}}\) = \(\sqrt{\frac{7500}{250 \times 30}}\)
I = √1 = 1A

Question 16.
Calculate the quantity of heat produced if 2 A current flows for 10 minutes through a heating coil of an electric kettle having 100 Ω resistance?
Answer:
I = 2A,
t = 10 × 60 = 600 s,
R = 100 Ω
H = I²Rt
H = 2² × 100 × 600 = 240000 J

Question 17.
A potential difference of 230 V is applied across a circuit for 5 minutes. If the resistance in the circuit is as given below, calculate the current and heat in each case.
(a) 115 Ω
(b) 230 Ω
Answer:
V= 230 V, t = 5 × 60 = 300 s
(a) R = 115 Ω
Current, I = \(\frac{V}{R}\) = \(\frac{230}{115}\) = 2A
Heat, H = VIt = 230 × 2 × 300
H = 138000 J

(b) R = 230 Ω
Current, I = \(\frac{V}{R}\) = \(\frac{230}{230}\) = 1A
Heat, H = VIt = 230 × 1 × 300
H = 69000 J

Question 18.
Observe the circuits given below. Calculate the quantity of heat produced in each, in 5 minutes.

Answer:

Heat produced in circuit 5.6(a)	Heat produced in circuit 5.6(b)	Heat produced in circuit 5.6(c)
H = I2Rt = 0.25 × 0.25 × 48 × 300 = 900 J	H = I2Rt = 0.5 × 0.5 × 24 × 300 = 1800 J	H = I2Rt = 1 × 1 × 1 × 300 = 3600 J

Question 19.
Analysing the completed table, answer the following questions.
a) What is the difference in the quantity of heat in circuits 5.6 (a) and 5.6 (b)?
Answer:
Heat in circuit 5.6 (a) = 900 J
Heat in circuit 5.6 (b) = 1800 J
Difference in quantity of heat = 1800 – 900
= 900 J

b) Why is there a difference in the quantity of heat produced in these circuits?
Answer:
Even though the voltage and time are the same, different combinations of current and resistance cause a variation in the amount of heat generated. In particular, even with a lower resistance, the greater current in circuit 5.6 (b) -0.5 A when compared to 0.25 A in 5.6 (a) results in a considerably greater I² term, which generates more heat.

c) What is the resistance of the circuit in figure 5.6 (c)?
Answer:
12 Ω

d) What is the total heat produced in the circuit in figure 5.6 (c)?
Answer:
H = 3600 J

e) Less heat is produced in the resistor of higher resistance in the circuit in figure 5.6 (a). Why?
Answer:
When the current is constant, the heat generated is directly proportional to the resistance, as stated by Joule’s law (H = I²Rt). However, a larger resistance results in a smaller current (I = V/R) if the voltage is constant, for all these three circuits. The effect of square of current mainly contributes to heat generated because heat is dependent on I²R. Therefore, less heat is produced in the resistor of higher resistance in the circuit in figure 5.6 (a).

f) Among these circuits, in which resistor is the maximum quantity of heat produced?
Answer:
In the 12 resistor in circuit 5.6(c)

g) What are your inferences? Record them in the science diary.
Answer:
If voltage is constant, when the resistance in the circuit is decreased, the current increases. Hence the quantity of heat produced increases.

Question 20.
If the voltage remains constant, what change will occur in the quantity of heat produced when the resistance varies? Explain based on Joule’s law.
Answer:
Joule’s law is given by H = I²Rt. However, when the voltage (V) is constant, expressing the current using Ohm’s law and substituting in joule’s law, we get H = \(\frac{V^2 t}{R}\). This equation shows that the heat generated (H) is inversely proportional to the resistance (R) when V and t are constant. This indicates that as resistance increases, heat generated decreases and when resistance decreases heat generated increases.

Question 21.
Calculate the quantity of heat produced if 2 A current flows through an electric heater operating at 230 V for 15 minutes. What is the resistance of the heater?
Answer:
I = 2A, t = 15 × 60 = 900s, V = 230 V
Heat produced, H =VIt
H = 230 × 2 × 900 =414000 J
Resistance of the heater = R = \(\frac{V}{I}\)
R = \(\frac{230}{2}\) = 115

Question 22.
An electric iron operating at a potential difference of 230 V has a heating coil of resistance 100 £2. If this electric iron operates for half an hour, how much electric energy will be converted to heat energy? What is the current through the electric iron?
Answer:
V = 230 V, R = 100 Ω, t = 30 × 60 = 1800 s
H = \(\frac{V^2 t}{R}\)
H = \(\frac{230^2 \times 1800}{100}\)
Current through the electric iron, I = \(\frac{V}{I}\) = \(\frac{230}{100}\) = 2.3 A

Question 23.
A heating appliance having a resistance of 92 Ω operates at 230 V. Using various equations, calculate the heat produced by the appliance in 14 minutes and write them down in the table below. What resistance is needed to double the heat energy?

Answer:

H = I2Rt	H = \(\frac{V^2 t}{R}\)	H = VIt
V = 230 V R = 92 Ω t = 14 minute = 14 × 60 = 840s I = \(\frac{V}{R}\) = \(\frac{230 \mathrm{~V}}{92 \Omega}\) = 2.5 A H = I2Rt = (2.5)2 × 92 × 840 J = 483000 J	V = 230 V R = 92 Ω t = 14 minute = 14 × 60 = 840s H = \(\frac{V^2 t}{R}\) H = \(\frac{230^2 \times 840}{92}\) = 483000 J	V = 230 V I = \(\frac{V}{R}\) = \(\frac{230 \mathrm{~V}}{92 \Omega}\) = 2.5 A t = 14 minute = 14 × 60 = 840 s H = VIt H = 230 × 2.5 × 840 = 483000 J

As the voltage and time is remaining constant, we take H = \(\frac{V^2 t}{R}\)
For H to become 2H(to double the heat energy),
we need to find new resistance value-R_new
2H = \(\frac{\mathrm{V}^2 \mathrm{t}}{\mathrm{R}_{\text {new }}}\)
We have 2\(\frac{V^2 t}{R}\) = \(\frac{\mathrm{V}^2 \mathrm{t}}{\mathrm{R}_{\text {new }}}\), \(\frac{2}{R}\) = \(\frac{1}{\mathrm{R}_{\text {new }}}\)
R_new = \(\frac{R}{2}\) = \(\frac{92}{2}\) = 46 Ω

Question 24.
Observe the values given on the label of the appliance in figure 5.7. What does marking 750 W indicate?

Answer:
750 W indicates the power at which the appliance work.
Energy conversion occurs when an appliance operates, is the work done. The quantity of work done per unit time is power. Power is the rate of work based on time.

Question 25.
The power of each electric appliance is marked on it. Complete the table given below.

Answer:

Device	Power (P)W	Energy consume in 1 second (Pt = p × 1)
LED Bulb	9	= 9 × 1 = 9 J
Projector	100	= 100 × 1 = 100 J
Fan	60	= 60 × 1 = 60 J
Laptop	40	= 40 × 1 = 40 J

While labelling the power of an appliance, the voltage at which it is to be operated is also indicated. In our country, the power obtained while operating at 230 V is labelled on electrical appliances. If the appliance operates above or below 230 V, the power will vary accordingly. That is, if the voltage increases, the power increases and if the voltage decreases, the power also decreases. This may lead to the damage of appliances. (There are also some appliances that operate at 400 V).

Countries design electrical appliances and power according to their power supply voltage. In all electrical appliances, the voltage required for it and its power will be marked on it. The indicated power is available from an appliance only when it operates at the specified voltage.

If the voltage is constant, according to P = \(\frac{V^2}{R}\), appliances with higher resistance will have lower power, and those with lower resistance will have higher power. While solving numerical problems related to household appliances, it is more desirable to use the formula P = \(\frac{V^2}{R}\). In some foreign countries, the supply voltage is 110 V.

Question 26.
At what applied voltage will an electric heating appliance marked 800 W, 240 V produce a power of 200 W?
Answer:
P₁ = 800W, V₁ = 240 V
R = \(\frac{\mathrm{V}_1^2}{\mathrm{P}}\) = \(\frac{240^2}{800}\)
R = 72 Ω
P₂ = 200 W, V₂ = ?
V₂² = P₂ × R
V₂² = 200 × 72 = 14400
V₂ = \(\sqrt{14400}\) = 120 V
Whenever voltage becomes half, power becomes 1/4 times the original power.

Question 27.
Calculate the quantity of heat produced when a heating appliance of power 500 W operates for five minutes.
Answer:
P = 500 W
t = 5 min = 5 × 60 = 300 s
H = Pt = 500 × 300 J = 150000 J

Question 28.
How much heat energy is produced when an electric heater with 600 W power operates for 20 minutes?
Answer:
P = 600 W, t = 20 × 60 = 1200 s
H = Pt = 600 × 1200 = 720000 J

Question 29.
How much heat energy will be produced if a heating appliance with 250 W power operates for 10 minutes?
Ans:
P = 250 W, t = 10 × 6 = 600 s
H = Pt = 250 × 600 = 150000 J

Question 30.
An electric heater produced 450000 J of heat energy when operated for 5 minutes. What would be the power of this heater?
Answer:
H = 450000 J, t = 5 × 60 = 300 s
H = Pt, P = \(\frac{H}{t}\)
P = \(\frac{450000}{300}\) = 1500 W

Question 31.
On a heating appliance it is marked 529 W, 230 V.
a) What do each of these mean?
b) What would be the power of this appliance if 100 V is supplied?
Answer:
a) 529 W, 230 V indicates that the appliance operating at voltage of 230 V consumes 529 W power.

b) R = \(\frac{\mathrm{V}^2}{\mathrm{P}}[latex] = [latex]\frac{230^2}{529}[latex] = 100 Ω
P = [latex]\frac{\mathrm{V}^2}{\mathrm{R}}[latex]
P = [latex]\frac{100^2}{100}[latex] = 100 W

Question 32.
Calculate the energy consumed by a 1 kW power appliance in one hour.
Answer:
E = Pt = 1kW × 1h
= 1kWh

One kilowatt hour or one unit of electric energy is the energy consumed by an appliance with 1000 W (1 kW) power in one hour.

One unit of electric energy in joules

1000W = 1kW

Energy consumed,
E = H = Pt
P = 1000W, t = 1 h = 60 × 60s
El = 1000 × 60 × 60 J
= 3600000 J = 3.6 × 10⁶ J

1kWh = one unit of electric energy = 3.6 × 106 J

Question 33.
How much heat energy will be produced when a heating appliance of 60 W operates for one hour?
Answer:
H = Pt
= 60 × 1 × 60 × 60 J
= 216000 J

Question 34.
The power and operating time of some appliances are given in the table. Complete the table.

Answer:

Power of device (P)W	Time (t)h	Electric energy spent (Pt) J	Energy utilized in unit (kWh) = [latex]\frac{\text { Power in watt }}{1000}\) × hour
1000	1 hour	1000 × 60 × 60 = 3600000 J	1k Wh = 1 unit
2000	1 hour	2000 × 60 × 60 = 7200000 J	2k Wh = 2 unit
500	1 hour	500 × 60 × 60 = 1800000 J	0.5 kWh = 0.5 unit
500	2 hour	500 × 2 × 60 × 60 = 3600000 J	Ik Wh = 1 unit

Question 35.
Calculate the electric energy consumed if a 500 W grinder and a 600 W electric iron each operate for 2 hours.
Answer:
Total power in watt = 500 W + 600 W
Time = 2 h
Electric energy (in kilo watt hour)
= \(\frac{\text { Power in watt × time in hour }}{1000}\)
= \(\frac{1100 \mathrm{~W} \times 2 \mathrm{~h}}{1000}\)
= 2.2 kWh
= 2.2 unit
Using this formula, we can calculate the monthly consumption of electricity.

Question 36.
Considering the total power of the appliances used and their operating time, calculate the daily electricity consumption in your house. Similarly, calculate the monthly consumption of electricity and present in class the main findings and suggestions based on the project report.
Answer:
An example is given below
• Prepare a table listing the given information

Appliance	Power (Watt)	Hours used per day	Number of appliances
Fan	75 W	10 hours	3
Tube light	40 W	6 hours	4
Television	100 W	4 hours	1
Refrigerator	150 W	24 hours	1
Washing Machine	500 W	1 hour	1
Steamer	1000 W	0.5 hours	1

• Calculate energy consumption in a day
  Electric energy (in kilowatt hour)

= 8.21 kWh = 8.21 units

• Calculate energy consumption in a month (30 days) = 8.21 × 30 = 246.3 units
• Analyze the findings. Identify which were among the high consuming appliances.
• Compare with energy consumption pattern in the previous month.
• Take action if the energy consumption is increased very much.
• Some actions that can be taken are
  • Turn off appliances when not in use to save energy.
  • Use energy-efficient appliances (like LED lights).
  • Avoid using high-power devices unnecessarily (like steamer).
  • Use natural light during the day to reduce lighting load.
  • Consider installing solar panels for long-term savings.
• Stay alert of your energy consumption by tracking it,which helps you to take appropriate action whenever necessary.

All houses have the different electricity tariff. Electricity charges are levied at a higher rate from consumers who use more electricity and at a lower rate from consumers who use less electricity. (Table 5.8)

Now we can understand that one of the reasons for the increased consumption of electricity is the unwanted and careless consumption of electricity. The amount in the electricity bill can be reduced by lowering electricity consumption.

Question 37.
What can we do to reduce electricity consumption at home?
Answer:

• Use energy efficient electrical appliances.
• Turn off switches immediately after use.
• Use LED tubes and bulbs.
• Choose the size of the fan according to the size of the room.
• Use BLDC fans. [BLDC – Brush Less Direct Current]
• Electronic appliances should be unplugged while not in use.
• Switch to energy star rated appliances which helps in reducing electricity bills, have less environmental impact and government benefits are applicable to them. (Like offer rebates or incentives to purchase them)

Further activities to reduce energy consumption can be implemented under the leadership of the School Energy Club in collaboration with the Energy Management Centre (EMC).

Question 38.
Do large scale electricity generating power plants cause environmental impacts? Discuss.
Answer:
Large scale electricity generating power plants are important for providing power to cities, industries, and homes. They produce a large amount of electricity and offer a steady and reliable supply. However, many of these plants, especially those using coal or gas, cause serious environmental problems like air pollution, global warming, and water pollution. They often use large amounts of water and land, which can harm wildlife and displace communities. Large scale hydropower projects can cause environmental problems. They often lead to the destruction of forests, loss of wildlife habitats, and the shifting of people due to dam construction. These projects can also disrupt river ecosystems. But compared to thermal and nuclear power plants hydro power is a reliable alternative. There are some demerits in all, but ways are to be identified to tackle the disadvantages. Switching on to other renewable energy sources which causes less pollution can become a smart and sustainable solution to the energy and environmental challenges caused by other large scale power plants.

Observe figure 5.9.
There are ways to produce electricity without causing pollution.

You know that the sun is the basis of all energy on the earth.

Question 39.
List the devices that utilise solar energy.
Answer:
• Solar water heater
• Solar cooker
• Solar furnace

Solar cells, panels and power plants
Solar cells are devices that convert solar energy into electric energy. Only negligible voltage and current can be obtained from a single cell. Therefore, a solar panel is constructed by arranging many solar cells suitably to provide electricity as per the requirement. The electricity obtained from such panels can be stored in a storage battery and utilised when needed. Or it can be directly supplied to the electricity distribution agencies. Solar panels are used for energy requirements in artificial satellites. In addition to small scale requirements, large scale solar power plants are also in operation.

• Cochin International Airport Limited (CIAL) in Nedumbassery, Kerala, produces electricity required for its entire operations from such a solar power plant.
• Cochin International Airport is the world’s first airport to operate entirely on solar power.

Question 40.
List the benefits of installing solar panels.
Answer:

• Can produce electricity required for homes.
• Can reduce environmental pollution.
• Transmission and distribution losses are minimised as electricity is generated at the place of consumption.

It is understood that atmospheric pollution is reduced when solar panels are used. We know that the quantity of greenhouse gases in the atmosphere is increasing daily. An increase in such gases cause global warming, resulting in climate change. Each of our interventions in this matter is very important. Global warming can be reduced by reducing the production of major greenhouse gases like carbon dioxide, methane etc. We need activities that can reduce the quantity of carbon and carbon compounds emitted by individuals, organisations, and products.

Question 41.
What can be done to reduce carbon footprint?
Answer:

• Reduce domestic energy consumption.
• Avoid wasting food.
• Use public transport.
• Reduce waste by utilising reusable products.
• Educate society about reducing carbon footprint.
• Perform energy consuming activities in an energy saving manner.

Question 42.
Prepare a seminar paper on how to reduce individual carbon footprint and present it in class.
Answer:
An example is given below.
Introduction
One of the most significant issues our world is facing now is climate change. It is mostly brought on by gases like carbon dioxide that are emitted into the atmosphere as a result of things like using electricity, driving a car, and creating garbage. These gases raise Earth’s temperature by trapping heat in the atmosphere, which can result in hazardous weather and environmental changes. Every individual’s, everyday activities add to this issue, and their carbon footprint is the overall quantity of greenhouse gases they create. Lowering carbon footprint helps in slowing down climate change and thus helps in preserving the earth for future generations, so lowering it is cmcial. We may take action to lessen our carbon footprint by being aware of its origins.

Methods for Lowering Carbon Footprint

• Conserve energy at home-When not in use, turn off fans, lights, and electrical equipment. Reduce the amount of electricity you use by using energy-efficient appliances and bulbs.
• Choose for greener transportation-Whenever feasible, take public transportation, walk, or cycling instead of driving a car. Carpooling with friends or travel mates reduces emissions as well. It is even better to use electric or fuel- efficient vehicles.
• Reducing, reusing, and recycling-Reduce the use of plastic bags and bottles. Use reusable bags and bottles instead of single-use plastics. Recycling glass, plastic, and paper contributes to a decrease in pollution and waste.
• Conserve water-As you brush your teeth, turn off the faucets and promptly address any leaks. Conserving water also reduces the energy required for water treatment.
• Encourage environmentally friendly products- Purchase goods that are manufactured sustainably and with less packaging. More green activities are encouraged when businesses that care about the environment are supported.
• Raise awareness-Discuss with loved ones the significance of lowering carbon footprints. To have a greater influence, join or form school-based environmental organizations.

Conclusion
It is not very easy to reduce carbon footprint, yet when many people make minor changes in their daily lives, the impact may be significant. Each of us may contribute to protecting the planet by minimizing trash, eating sensibly, adopting more environmentally friendly transportation, conserving energy, and raising awareness. Together we can make the planet a better and cleaner place to live.

‘Reducing atmospheric pollution and conserving energy is everyone’s duty. Energy conservation is equivalent to energy production. ’

‘Energy is precious, don’t waste it! ’

Std 10 Physics Chapter 5 Notes – Extended Activities

Question 1.
Observe the electricity bill of your house and find out the monthly electricity consumption. Present activities that can be implemented in your house to reduce electricity consumption in a seminar in the Energy Club. Also, prepare necessary posters for this.
Answer:
By observing the electricity bill one can find out the monthly electricity consumption. Total units consumed and amount to be paid can be identified and it can be compared with previous month to understand the pattern of energy consumption.

Activities that can be implemented to reduce electricity consumption

• Make a transition to energy-efficient appliances.
• Maximize the performance of your air conditioning and heating systems.
• Use LED bulbs-LEDs use less power and last longer than normal bulbs.
• Turn off electrical appliances when not in use-Always switch off fans, lights, and appliances when you leave a room.
• Unplug devices-Chargers, TVs, and microwaves still use power when plugged in. So electronics should be unplugged while not in use.
• Use natural light during the day-Open curtains and windows instead of turning on lights.
• Use washing machine for full loads only-This saves both electricity and water.
• Limit geyser use-Use it only for a short time and turn it off immediately after use.
• Check your meter weekly-Keep a track of electricity consumption which will make you aware of the
  energy usage.

Switch Off to Switch On a Better Future

Save Energy, Save Earth

Question 2.
List the activities that the School Science Club intends to undertake to reduce the school’s carbon footprint.
Answer:

• Plan tree-planting activities and create green spaces on the school’s property.
• To reduce waste, set up recycling facilities and encourage the use of reusable products.
• When not in use, remind employees and students to turn off lights and electronics.
• Encourage water-saving practices including repairing leaks and properly shutting off taps.
• Increase public knowledge of climate change and sustainability through seminars, discussions, and initiatives.
• Encourage environmentally sustainable modes of transportation, such as walking, bicycling, or ridesharing, to get to school.
• Initiate the process , of composting organic waste for school gardens.
• Examine the school’s energy usage on a regular basis and make recommendations for ways to reduce , electricity use.
• Join local or national green projects by working with environmental organizations.
• Reduce the amount of plastic used in the cafeteria and promote eco-friendly options for school supplies.

Electric Energy: Consumption and Conservation Class 10 Notes

Electric Energy: Consumption and Conservation Notes Pdf

• The conversion of electric energy mainly into heat energy is the heating effect of electric current. Appliances that utilise this effect are electric heating appliances. –
• The process of production of heat, when electricity flows through a conductor is Joule heating or Ohmic heating. The part used to produce heat energy in heating appliances is the heating element.
• The resistance of a conductor with an area of cross section of one square metre and a length of one metre is the resistivity of the material of the conductor. It is denoted by the Greek letter ρ(rho). Its unit is ohm metre (Ωm).
• Conductivity is the ability of a material to conduct electricity. This is the reciprocal of resistivity.
• The factors which influence the resistance of a conductor are length of the conductor (l), area of cross section (A) and the nature of the material (ρ). The relation of resistance (R) with these factors is given by the equation R = \(\frac{\rho l}{A}\)
• Factors that influence the quantity of heat produced in a current carrying conductor are
  • Current (I)
  • Resistance of the conductor (R)
  • Time for which current flows (t)
• The quantity of heat produced in a current carrying conductor is directly proportional to the square of the current (I²) the resistance of the conductor (R) and the time (t) for which the current flows. This is Joule’s law.
• If a current I flows through a conductor having resistance R for a time t, according to Joule’s law, the quantity of heat produced will be H = I²Rt. Its SI unit is joule (J).
• Power is the quantity of work done by an electrical appliance per unit time. The work done by an electrical appliance is the conversion of electric energy into another form of energy.
• The quantity of electric energy consumed in houses can be measured directly by a watt-hour meter connected to our household electric circuit. In this, electric energy is measured in kilowatt hour (kWh) units. This is the commercial unit of electric energy.
• One kilowatt hour or one unit of electric energy is the energy consumed by an appliance with 1000 W (1 kW) power in one hour.
• Energy crisis is the increase in demand for energy and the decrease in availability.
• Solar cells are devices that convert solar energy into electric energy.
• Greenhouse gases are directly and indirectly emitted by individuals, families, organizations, events, services, products, etc. The quantity of such emitted greenhouse gases, converted and expressed as equivalent to the measure of carbon dioxide, is carbon footprint.

INTRODUCTION

Electricity plays a crucial role in our everyday activities and is used in many forms. This chapter explores how electrical energy can be transformed into other types of energy, such as heat, light, and mechanical energy. A key topic is Joule heating, which explains how electric current produces heat in wires and devices. We also learn about electric power, which tells us the rate at which electrical energy is used, and how it is measured using a watt-hour meter. The electricity used in homes is measured in kilowatt-hours (kWh), which is the standard commercial unit. Excessive use of energy, especially from non-renewable sources, contributes to the energy crisis and increases our carbon footprint, damaging the environment. To solve these problems, switching to solar energy and other renewable sources is a cleaner and more sustainable option.

Heating effect of electric current

• The useful form of energy into which an appliance mainly converts electric energy is considered the effect of electric current in that appliance.
• The conversion of electric energy mainly into heat energy is the heating effect of electric current. Appliances that utilise this effect are electric heating appliances.
• The process of production of heat, when electricity flows through a conductor is Joule heating or Ohmic heating. The part used to produce heat energy in heating appliances is the heating element. The heating coil is made of an alloy, nichrome.

Resistivity and conductivity

• The resistance of a conductor with an area of cross section of one square metre and a length of one metre is the resistivity of the material of the conductor. It is denoted by the Greek letter ρ(rho). Its unit is ohmmetre (Ωm).
• Conductivity is the ability of a material to conduct electricity. This is the reciprocal of resistivity.
• The factors which influence the resistance of a conductor are length of the conductor (l), area of cross section (A) and the nature of the material (ρ). The relation of resistance (R) with these factors is given by the equation R = \(\frac{\rho l}{A}\)
• Factors that influence the quantity of heat produced in a current carrying conductor are
  • Current (I)
  • Resistance of the conductor(R)
  • Time for which current flows(t)

Joule’s law of heating

• The quantity of heat produced in a current carrying conductor is directly proportional to the square of the current (I²), the resistance of the conductor (R) and the time (t) for which the current flows. This is Joule’s law.
• If a current I flows through a conductor having resistance R for a time t, according to Joule’s law, the quantity of heat produced will be H = I²Rt. Its SI unit is joule (J).

Electric power

• Power is the quantity of work done by an electrical appliance per unit time. The work done by an electrical appliance is the conversion of electric energy into another form of energy.
• The quantity of electric energy consumed in houses can be measured directly by a watt-hour meter connected to our household electric circuit. In this, electric energy is measured in kilo watt hour (kWh) units. This is the commercial unit of electric energy.
• One kilowatt hour or one unit of electric energy is the energy consumed by an appliance with 1000 W (1 kW) power in one hour.

Energy crisis
• Though the demand for energy has increased many folds, production has not sufficiently increased. This situation is energy crisis. Simply, we say Energy crisis is the increase in demand for energy and the decrease in availability.

Solar cells, panels and power plants

• Solar cells convert sunlight into electrical energy, but a single cell produces only a small amount of power.
• To meet higher energy needs, many cells are combined to form solar panels, which can store electricity in batteries or supply it to the power grid.
• Solar panels are used in satellites, homes, and large-scale solar power plants for energy production with less pollution.

Carbon footprint

• Greenhouse gases are directly and indirectly emitted by individuals, families, organizations, events, services, products, etc. The quantity of such emitted greenhouse gases, converted and expressed as equivalent to the measure of carbon dioxide, is carbon footprint.
• Each individual should strive to reduce his/her personal carbon footprint. This can be achieved by paying attention to daily activities.

HEATING EFFECT OF ELECTRIC CURRENT
The conversion of electric energy mainly into heat energy is the heating effect of electric current. Appliances that utilise this effect are electric heating appliances.

ELECTRIC POWER
Power is the quantity of work done by an electrical appliance per unit time. The work done by an electrical appliance is the conversion of electric energy into another form of energy.

The function of electric heating appliances is to produce heat. You have learnt that the quantity of heat produced
H = I²Rt
Work = quantity of heat produced
W = H = I²Rt
Equation to find electric power
Power = \(\frac{Work}{time}\)
P = \(\frac{W}{t}\) = \(\frac{H}{t}\)
P = \(\frac{I^2 R t}{t}\)
P = I²R
According to Ohm’s law, I = \(\frac{V}{R}\)
Then P = \(\frac{V^2}{R}\)
We know that R = \(\frac{V}{I}\)
Hence P = VI
We will get the equations = P = \(\frac{V^2}{R}\), P = VI
P = I²R = \(\frac{V^2}{R}\) = VI
If we substitute the value of P in the equations used to calculate heat, H = I²Rt.We get
H = Pt
It is understood that the quantity of heat produced in a given time can be found if the power of an appliance is known.

Watt-hour meter

The quantity of electric energy consumed in houses can be measured directly by a watt hour meter connected to our household electric circuit. In this, electric energy is measured in kilowatt hour (kWh) units. This is the commercial unit of electric energy. Power is expressed in watt, time in second, and energy in joule.

The energy consumed if a 9 W bulb operates for one hour daily for 30 days is E = Pt = 9 × 30 × 3600J = 972000J (nine lakh seventy two thousand joules). So, if we consider the monthly energy consumption of all the appliances in a house, the total would be very large, making it inconvenient to record. Therefore, energy is calculated in kilowatt hour by measuring power in kilowatt and time in hour.

ENERGY CRISIS
Despite having many small scale electricity projects in addition to large power stations, the electricity they produce is not sufficient for our needs. Though the demand for energy has increased many folds, production has not sufficiently increased. This situation is energy crisis. This is why sometimes power cuts and load shedding are to be implemented.

‘Energy crisis is the increase in demand for energy and the decrease in availability.’

There are hydroelectric power plants, thermal power plants, nuclear power plants, etc., to produce electricity on a large scale. Yet, it is not easy to increase the electricity production.

Rooftop power project
Solar panels can be installed on rooftops of houses and other places receiving sunlight. The Rooftop Power Project is a scheme jointly initiated by the Central Government and KSEB for this purpose.

Carbon footprint
Greenhouse gases are directly and indirectly emitted by individuals, families, organizations, events, services, products, etc. The quantity of such emitted greenhouse gases, converted and expressed as equivalent to the measure of carbon dioxide, is carbon footprint.

Each individual should strive to reduce his/her personal carbon footprint. This can be achieved by paying attention to daily activities. How one travels, what food one eats, what clothes one uses, and how much waste is generated are all important.

Parents often use SCERT Kerala Syllabus 8th Standard English Notes Pdf Unit 3 Chapter 2 Engine Trouble Questions and Answers Activities Notes to assist their kids with homework.

Class 8 English Engine Trouble Question Answer Activities

Engine Trouble Questions and Answers Class 8

8th Standard English Engine Trouble Question Answer

Question 1.
What do you think of the child’s question in the first stanza? Have you ever felt the same way?
ആദ്യത്തെ സ്റ്റാൻസയിലെ കുട്ടിയുടെ ചോദ്യത്തെക്കുറി ച്ച് നിങ്ങൾ എന്ത് കരുതുന്നു? നിങ്ങൾക്ക് എപ്പോഴെ ങ്കിലും അതുപോലെ തോന്നിയിട്ടുണ്ടോ?
Answer:
I think the child’s question is very innocent and imaginative. It shows how a child sees the world poetically, thinking the moon is physically close and can be caught like a fruit in a tree. Yes, I have felt the same way. When I was younger and travelling in a car, I used to think the moon was following me.

Question 2.
What is Dada’s answer to the child’s question?
കുട്ടിയുടെ ചോദ്യത്തിന് ദാദയുടെ മറുപടി എന്തായിരുന്നു?
Answer:
Dada’s answer is based on scientific facts. He explains that the moon cannot be caught because it is very far away from us and is also very big, even though it appears small.

Question 3.
Do you think the child is convinced by Dada’s arguments? Why/Why not?
ദാദയുടെ വാദങ്ങൾ കുട്ടിക്ക് ബോധ്യപ്പെട്ടുവെന്ന് നിങ്ങൾ കരുതുന്നുണ്ടോ? എന്തുകൊണ്ട്/എന്തുകൊണ്ടില്ല?)
Answer:
No, the child is not convinced by Dada’s arguments. The child continues to argue back with his own emotional logic, comparing the moon’s apparent size and distance to his mother’s loving face. This shows the child sees the world from a different, more imaginative perspective.

Question 4.
How does the poem capture the innocence and imagination of childhood? Quote specific lines from the poem to support your answer.
കുട്ടിക്കാലത്തിന്റെ നിഷ്കളങ്കതയും ഭാവനയും ഈ കവിത എങ്ങനെയാണ് ഒപ്പിയെടുക്കുന്നത്? നിങ്ങ ളുടെ ഉത്തരത്തെ പിന്തുണയ്ക്കാൻ കവിതയിൽ നിന്ന് പ്രത്യേക വരികൾ ഉദ്ധരിക്കുക.
Answer:
The poem captures the innocence and imagination of childhood by showing the contrast between a child’s poetic view and an adult’s scientific view. The child connects the world to feelings and love.

• Line for imagination: “…When in the evening the round full moon gets entangled among the branches… couldn’t somebody catch it?” This shows the child imagines the moon is a small object trapped nearby.
• Line for innocence: “When mother bends her face down to kiss us, does her face look very big?” – This shows the child’s innocent logic, where emotional closeness is more important than physical size.

Question 5.
What does the conversation between the child and Dada reveal about their relationship?
കുട്ടിയും ദാദയും തമ്മിലുള്ള സംഭാഷണം അവർ തമ്മി ലുള്ള ബന്ധത്തെക്കുറിച്ച് എന്ത് വെളിപ്പെടുത്തുന്നു?
Answer:
The conversation reveals a close, loving, and playful relationship. Even though Dada calls the child “silly” or “stupid,” it is said affectionately. The child feels comfortable enough to argue back and call Dada “foolish,” which shows they have a strong and informal bond.

Engine Trouble Class 8 Question Answer – Let’s appreciate:

A. (i) Why does the child compare the moon to the mother’s face? Do you think the child’s logic is mistaken, or truly insightful?
എന്തുകൊണ്ടാണ് കുട്ടി ചന്ദ്രനെ അമ്മയുടെ മുഖ വുമായി താരതമ്യം ചെയ്യുന്നത്? കുട്ടിയുടെ യുക്തി തെറ്റാണെന്നാണോ അതോ ശരിക്കും ഉൾക്കാഴ്ചയുള്ള താണെന്നാണോ നിങ്ങൾ കരുതുന്നത്?
Answer:
The child compares the moon to the mother’s face because, to the child, both are sources of love, comfort, and beauty. The child’s logic is scientifically mistaken, but poetically, it is truly insightful. It shows a deeper wisdom that nearness and importance are felt through love, not just by physical distance or size.

(ii) What is the difference in perception between the child and Dada? Which perspective appears more convincing to you? Why?
കുട്ടിയും ദാദയും തമ്മിലുള്ള കാഴ്ചപ്പാടിലെ വ്യത്യാ സം എന്താണ്? ഏത് കാഴ്ചപ്പാടാണ് നിങ്ങൾക്ക് കൂടു തൽ ബോധ്യപ്പെടുന്നത്? എന്തുകൊണ്ട്?)
Answer:
The main difference is that the child’s perception is emotional and imaginative, while Dada’s perception is scientific and logical. The child sees the world through the heart, whereas Dada sees it through his brain. (This is a personal choice) While Dada’s perspective is factually correct, the child’s perspective is also convincing because it reminds us of the importance of imagination and looking at the world with a sense of wonder.

B. In the poem we listen to the innocent questions of a child on the world around it. Here is the transcript of a conversation between a child and its father. You may read it and try to fill in the gaps:
Child: I always wonder, dad, why do the waves of the sea lash out endlessly? Don’t they get tired?
Dad: ………………………………………………………………………………………
Child: Can’t we stop the waves?
Dad: ………………………………………………………………………………………
Child: The power of the waves is of no use, then?
Dad: Baby! Science may help us to use its power for our needs.
കവിതയിൽ, ഒരു കുട്ടി ചുറ്റുമുള്ള ലോകത്തെക്കുറിച്ച് ചോദിക്കുന്ന നിഷ്കളങ്കമായ ചോദ്യങ്ങൾ നമ്മൾ കേൾക്കുന്നു. ഇവിടെ ഒരു കുട്ടിയും അച്ഛനും തമ്മിലുള്ള സംഭാഷണം നൽകിയിരിക്കുന്നു. അത് വായിച്ച് വിട്ടഭാഗങ്ങൾ പൂരിപ്പിക്കാൻ ശ്രമിക്കുക
Answer:
Child: I always wonder, dad, why do the waves of the sea lash out endlessly? Don’t they get tired?
Dad: That’s a lovely question! No, dear. The wind gives them the energy to keep dancing always.
Child: Can’t we stop the waves?
Dad: No, we can’t. The ocean is too powerful for us to stop its waves.
Child: The power of the waves is of no use, then?
Dad: Baby! Science may help us to use its power for our needs.

Engine Trouble Activities

Class 8 English Engine Trouble Activities Pdf – Let’s recall and recreate:

Activity 1

Let’s have fun generating images with All prompts.

A പ്രോംപ്റ്റുകൾ ഉപയോഗിച്ച് ചിത്രങ്ങൾ നിർമ്മിച്ച് രസിക്കാം
A. Now, it’s your turn. Think about the poem you have just read. What scene would you like to recreate? Is it that of a child looking at the moon? Let’s now create some prompts for images.

ഇനി നിങ്ങളുടെ ഊഴമാണ്. നിങ്ങൾ ഇപ്പോൾ വായിച്ച കവിതയെക്കുറിച്ച് ചിന്തിക്കുക. ഏത് രംഗമാണ് നിങ്ങ ൾ പുനഃസൃഷ്ടിക്കാൻ ആഗ്രഹിക്കുന്നത്? ചന്ദ്രനെ നോക്കു ന്ന കുട്ടിയുടെ ചിത്രമാണോ? നമുക്ക് ചിത്രങ്ങൾക്കായി ചില പ്രോംപ്റ്റുകൾ ഉണ്ടാക്കാം.
Answer:
Prompt 1: A small child in a village in India at night, pointing up excitedly at a large full moon that appears to be caught in the branches of a large tree.
Prompt 2: An innocent young child explaining something to his skeptical older brother.
They are both looking up at a starry night sky with a full moon. The child looks imaginative, and the brother looks amused.
Prompt 3: A child’s dream: The gentle, smiling face of a loving Indian mother is beautifully blended with the image of a full moon in a starry night sky.

B. What text prompt will generate the image below? Write it in the space provided.

താഴെ നൽകിയിട്ടുള്ള ചിത്രം നിർമ്മി ക്കാൻ എന്ത് ടെക്സ്റ്റ് പ്രോംപ്റ്റ് ആണ് നൽകേണ്ടത്? ന ൽകിയിട്ടുള്ള സ്ഥലത്ത് അത് എഴുതുക.
Answer:

A realistic painting of a young boy with curly hair, seen from behind, looking out of an old wooden window at a beautiful sunrise over a peaceful Keralan village. The scene outside includes lush green coconut trees, tropical plants, and a small hut with a tiled roof. The sky is filled with the warm, golden and orange light of the early morning.

Std 8 English Engine Trouble Question Answer – Let’s play with words

Activity 1

Puzzle Power: Boost Your Brain!

പദപ്രശ്നം: നിങ്ങളുടെ തലച്ചോറിന് ഒരു ഉത്തേജനം!!
Answer:

Std 8 English Engine Trouble Question Answer – Activity 2

Let’s try to grasp the meaning of words in a creative way. We can draw simple scenes from the story and include dialogue or conversation using words from the passage, like ‘wobble’, ‘desperate’, ‘huge’, ‘showman etc.
Example: ‘showman’

Now, create situations to reinforce your understanding of words like ‘wobble,’ ‘desperate,’ ‘huge,’ etc. ഇനി, ‘wobble,’ ‘desperate,’ ‘huge,’
• …………………………………………………………………………………..
• …………………………………………………………………………………..
• …………………………………………………………………………………..
തുടങ്ങിയ വാക്കുകളെക്കുറിച്ചുള്ള നിങ്ങളുടെ ധാരണ ഉറപ്പിക്കുന്നതിനായി സന്ദർഭങ്ങൾ നിർമ്മിക്കുക.
Answer:
1. Situation for ‘wobble’
Scene: A child is learning to ride a bicycle for the first time in a park, with their father running alongside.

Dialogue
Child: “Dad, please don’t let go of the seat!”
Father: “I’m right here. Just try to pedal straight.”
Child: “Oh! The front wheel started to wobble dangerously when I turned. I nearly fell!”

2. Situation for ‘desperate’
Scene: A student is frantically searching their bag outside an examination hall, just minutes before the exam begins.
Dialogue:
Friend: “What’s wrong? The exam is about to start.”
Student: “I can’t find my hall ticket! I’ve checked my bag three times. I’m feeling desperate; I don’t know what to do!”

3. Situation for ‘huge’
Scene: Two friends are standing in front of a shopping mall that has just opened in their town.
Dialogue:
Friend 1: “Wow, I didn’t realize it would be this big.”
Friend 2: “I know! It’s a huge mall. They say it has over a hundred shops inside.”

Engine Trouble Class 8 Question Answer – Let’s analyse:

Activity 1

A. Read the following sentences and observe the difference between them.
താഴെ നൽകിയിട്ടുള്ള വാക്യങ്ങൾ വായിച്ച് അവ തമ്മി ലുള്ള വ്യത്യാസം നിരീക്ഷിക്കുക.
1. The narrator looks at the road engine every morning.
2. The narrator is looking at the road engine right now.
• What is the difference between these sentences?
……………………………………………………………………………
• When does the action take place in the first sentence, and when does it happen in the second sentence?
………………………………………………………………………………..
Answer:
The first sentence talks about a habitual action, about something in general /things that happen repeatedly at the same time every day. The second sentence describes an action happening at the present moment.

B. Read the following sentences and arrange them suitably in the table given.
താഴെ നൽകിയിട്ടുള്ള വാക്യങ്ങൾ വായിച്ച് അവയെ പട്ടികയിൽ അനുയോജ്യമായി ക്രമീകരിക്കുക.
• The water is boiling.
• She gets up early, every morning.
• They are going to school now.
• We live in a small town.
• It is raining heavily outside.
• They go to the seaside on weekends

Answer:

Habitual actions in the present time	Actions that are happening in the present moment
• She gets up early, every morning. • We live in a small town. • They go to the seaside on weekends.	• The water is boiling. • They are going to school now. • It is raining heavily outside.

C. Complete the following sentences.
താഴെ നൽകിയിട്ടുള്ള വാക്യങ്ങൾ പൂർത്തിയാക്കുക.
1. Reetu helps her classmates with their homework every day.
2. We usually share our lunch with friends who forget to bring theirs.
3. Now, they are planting trees in the park to make their neighbourhood greener.
4. I am preparing a thank you card for my teacher right now.
5. They volunteer at an orphanage every summer vacation.
6. Look! How patiently she is helping her younger brother to solve a problem.
7. Raju helps his parents with household chores every morning.

D. Rewrite the following sentences correctly, if necessary.
താഴെ നൽകിയിട്ടുള്ള വാക്യങ്ങൾ ആവശ്യമെങ്കിൽ ശരി യായി മാറ്റിയെഴുതുക.
Answer:
1. Look! That man tries to open the door.
………………………………………………………….
Answer:
Look! That man is trying to open the door.

2. Water boils at 100° C.
………………………………………………………….
Answer:
Water boils at 100° C. (Correct no change needed)

3. Arun is never late. He is getting to work on time.
……………………………………………………………………
Answer:
Arun is never late. He gets to work on time.

4. I must go now. It gets late.
………………………………………………………………
Answer:
I must go now. It is getting late.

E. Now, write five sentences on each of the following.
ഇനി, താഴെ പറയുന്ന ഓരോ വിഷയത്തിലും അഞ്ച് വാക്യങ്ങൾ വീതം എഴുതുക
1. Your daily habits (using the simple present).
നിങ്ങളുടെ ദിനചര്യകൾ – സിമ്പിൾ പ്രസന്റ് ടെൻസ് ഉപയോഗിച്ച്
Answer:

• I wake up at 6:30 every morning.
• I read the newspaper for half an hour.
• I go to school by bus.
• I play cricket with my friends in the evening.
• I do my homework before dinner.

2. Activities you are doing at the present moment.
നിങ്ങൾ ഇപ്പോൾ ചെയ്തുകൊണ്ടിരിക്കുന്ന പ്രവൃത്തികൾ
As a student doing homework
ഹോംവർക്ക് ചെയ്യുന്ന ഒരുവിദ്യാർത്ഥി എന്നനിലയിൽ
Answer:

• I am sitting at my study table now.
• I am writing answers in my English notebook.
• My brother is watching television in the next room.
• The fan is spinning above my head.
• My mother is cooking dinner in the kitchen.

F. Do you know that we use the simple present and the present continuous tense for other purposes as well? List a few such examples.
സിമ്പിൾ പ്രസന്റ്, പ്രസന്റ് കണ്ടിന്യൂസ് ടെൻസുകൾ മറ്റ് ആവശ്യങ്ങൾക്കും ഉപയോഗിക്കാറുണ്ടെന്ന് നിങ്ങ ൾക്കറിയാമോ? അത്തരം ചില ഉദാഹരണങ്ങൾ പട്ടി കപ്പെടുത്തുക
Answer:
Other uses of the Simple Present Tense:

• For future events that are part of a fixed timetable or schedule.
  Example: The train leaves at 9 p.m. tonight.
• In newspaper headlines.
  Example: Prime Minister visits Kerala.
• For universal truths and scientific facts.
  Example: The Earth revolves around the Sun

Other uses of the Present Continuous Tense:

• For definite future plans and arrangements.
  Example: We are visiting our grandparents this weekend.
• For complaining about annoying habits (usually with ‘always’).
  Example: He is always losing his keys.
• For temporary situations.
  Example: I usually walk to school, but this week I am taking the bus.

A Long Walk with Granny Class 8 Questions and Answers Pdf – Activity 2

A verb that requires an object for the sentence to make sense is a transitive verb.
A verb that does not require an object and is complete by itself is an intransitive verb.

A. Read the passage below:
As the sun set, Maria walked slowly along the beach. She picked up a beautiful shell and examined it carefully. The sound of the waves calmed her mind. She sat down on the sand and watched the stars twinkling. The peaceful atmosphere soothed her.

Pick out the transitive and intransitive verbs in the passage and note them in the space below.

താഴെ നൽകിയിട്ടുള്ള ഖണ്ഡിക വായിക്കുക. അതിലെ സകർമ്മക ക്രിയകളെയും (transitive verbs) അക ർമ്മക ക്രിയകളെയും (intransitive verbs) കണ്ട ത്തി താഴെ നൽകിയിട്ടുള്ള സ്ഥലത്ത് കുറിക്കുക.
Answer:

Transitive verbs	Intransitive verbs
pick	walk
examined	set
calmed	sat down
watched

A Long Walk with Granny Notes –  Activity 3

A. Look at the sentences given below and note the differences between them.
താഴെ കൊടുത്തിരിക്കുന്ന വാക്യങ്ങൾ നോക്കി അവ തമ്മിലുള്ള വ്യത്യാസങ്ങൾ കുറിക്കുക
1. The elephant pulled the road engine.
2. The road engine was pulled by the elephant
• Do they convey the same idea?
…………………………………………………………………….
• How is sentence ‘1’ different from sentence ‘2’?
……………………………………………………………………..
Answer:
In the first sentence, the subject (the elephant) is the performer/doer of the action. In the second sentence, the focus shifts to the object (the road engine), which now becomes the subject of the sentence.
In the first sentence the subject performs the action.
In the second sentence the action is performed by someone.

B. Now, look at the following sentences and observe the differences between the two, and write them down in the space provided.
Joseph helped the narrator.
The narrator was helped by Joeph.
…………………………………………………………………………………….
……………………………………………………………………………………
Answer:
When the subject performs the action, the sentence is in the active voice. In the passive voice, the object is given importance. The object of the sentence in the active voice becomes the subject of the sentence in the passive voice

C. Identify whether the following sentences are in the active or passive voice and rewrite them changing the voice.
താഴെ നൽകിയിട്ടുള്ള വാക്യങ്ങൾ കർത്തരി പ്രയോഗത്തി ലാണോ (active voice) കർമ്മണി പ്രയോഗത്തി
ലാണോ (passive voice) എന്ന് തിരിച്ചറിഞ്ഞ്, പയോഗം മാറ്റി എഴുതുക
Answer:
1. Joseph met the municipal chairman.

• Voice: Active Voice
• Changed Sentence: The municipal chairman was met by Joseph.

2. The request was not accepted by the chairman.

• Voice: Passive Voice
• Changed Sentence: The chairman. did not accept the request.

3. The municipality pressed them to clear out.

• Voice: Active Voice
• Changed Sentence: They were pressed by the municipality to clear out.

4. Joseph saw the priest of the local temple.

• Voice: Active Voice
• Changed Sentence: The priest of the local temple was seen by Joseph.

5. He was offered the services of the temple elephant by the priest.

• Voice: Passive Voice
• Changed Sentence: The priest offered him the services of the temple elephant.

D. Now, choose two sentences each in the active and the passive voice from the story, and rewrite them, changing the voice.
• ……………………………………………………………………….
• ……………………………………………………………………….
• ……………………………………………………………………….
ഇനി, കഥയിൽ നിന്ന് കർത്തരി പ്രയോഗത്തിലും കർ മ്മണി പ്രയോഗത്തിലുമുള്ള രണ്ട് വാക്യങ്ങൾ വീതം തിര ഞ്ഞെടുത്ത്, പ്രയോഗം മാറ്റി എഴുതുക.
Answer:
Active to Passive:
1. Original (Active): The elephant dragged the engine one way.
Changed (Passive): The engine was dragged one way by the elephant

2. Original (Active): The police marched me off.
Changed (Passive): I was marched off by the police.

Passive to Active:
1. Original (Passive): The school was founded by my father. (“The Day My World Changed”)
Changed (Active): My father founded the school.

2. Original (Passive): Several yards of compound wall had to be built by me. (“Engine Trouble”)
Changed (Active): I had to build several yards of compound wall.

Class 8 English A Long Walk with Granny Activities Pdf – Activity 4

A Read the lines below.
താഴെ നൽകിയിട്ടുള്ള വരികൾ വായിക്കുക.
I also took into service one joseph a dismissed bus driver who said that although he knew nothing of road rollers he could nevertheless steer one if it was somehow kept in motion

• Do these words convey meaning? Why not?
…………………………………………………..
ഈ വാക്കുകൾക്ക് അർത്ഥം നൽകാൻ കഴിയുന്നുണ്ടോ? എന്തുകൊണ്ടില്ല
Answer:
The words convey some meaning, but it is very difficult to understand it clearly. This is because there are no capital letters, commas, or full stops to show where one idea ends and another begins, making the sentence confusing to read.

• What difficulties do you notice when sentences are written without appropriate punctuation marks?
• Lack of clarity and sense.
• …………………………………………
• ……………………………………….
• ……………………………………….
ചിഹ്നങ്ങൾ ഇല്ലാതെ വാക്യങ്ങൾ എഴുതുമ്പോൾ എന്ത് ബുദ്ധിമുട്ടുകളാണ് നിങ്ങൾ കാണുന്നത്
Answer:

• Lack of clarity and sense.
• It is hard to know where to pause while reading.
• It becomes difficult to understand the tone of the sentence (e.g., whether it is a statement or a question).
• Names of people and places are not easily identified without capital letters.

B. Examine the punctuation marks listed below and identify their uses.
താഴെ നൽകിയിട്ടുള്ള ചിഹ്നങ്ങൾ പരിശോധിച്ച് അവ യുടെ ഉപയോഗങ്ങൾ കണ്ടെത്തുക.

1. Full stop (.)
• Use: It ends a sentence.
Example: She went to school yesterday.

2. Comma (,)
• Use: …………………………………………………………….
Example: I bought a laptop, a mouse pad, and a mobile phone.

3. Question Mark (?)
• Use: …………………………………………………………….
Example: …………………………………………………………….

4. Exclamation mark (!)
• Use: …………………………………………………………….
Example: …………………………………………………………….

5. Colon (:)
• Use: It introduces a list, an explanation, or an example.
Example: She brought three things: a pen, a notebook, and a calculator.

6. Quotation Marks (“ ”)
• Use: …………………………………………………………….
Example: ‘The Seven Ages of Man’.
She said, “I will be there soon.”

7. …………………………………………………………….
• Use: …………………………………………………………….
Example: …………………………………………………………….

8. …………………………………………………………….
• Use: …………………………………………………………….
Example: …………………………………………………………….
Answer:
1. Full stop (.)
• Use: It ends a sentence.
Example: She went to school yesterday.

2. Comma (,)
• Use: To separate items in a list or to separate different parts of a sentence.
Example: I bought a laptop, a mouse pad, and a mobile phone.

3. Question Mark (?)
• Use: It is used at the end of a direct question.
Example: Where are you going?

4. Exclamation mark (!)
• Use: It is used to show strong feelings like surprise, excitement, or anger.
Example: What a wonderful surprise!

5. Colon (:)
• Use: It introduces a list, an explanation, or an example.
Example: She brought three things:
a pen, a notebook, and a calculator.

6. Quotation Marks (“ ”)
• Use: To show the exact words some one said (direct speech) or for titles
Example: ‘The Seven Ages of Man’. She said, “I will be there soon.”

7. Apostrophe (‘)
• Use: To show possession (owner ship) and for contractions (short forms).
Example: This is Ravi’s pen. It’s a sunny day.

8. Semicolon (;)
• Use: To connect two closely related independent sentences.
Example: He loves playing cricket; his sister prefers to read books.

C. Now, use appropriate punctuation marks to rewrite the lines given in the beginning of Activity 4.
…………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………….
ഇനി, ആക്റ്റിവിറ്റി 4 – ന്റെ തുടക്കത്തിൽ നൽകിയിട്ടുള്ള വരികൾ അനുയോജ്യമായ ചിഹ്നങ്ങൾ ഉപയോഗിച്ച് മാറ്റിയെഴുതുക.
Answer:
I also took into service one Joseph, a dismissed bus-driver, who said that although he knew nothing of road-rollers, he could nevertheless steer one if it was some how kept in motion.

Students often refer to Kerala Syllabus 8th Standard English Textbook Answers and The Astronomer in Malayalam & English before discussing the text in class.

Class 8 English The Astronomer Summary

The Astronomer Summary in English

I only said, “When in the evening the
round full moon gets entangled
among the branches of that dadam
tree, couldn’t somebody catch it?”

But Dada laughed at me and said,
“Baby, you are the silliest child I
have ever known. The moon is ever so
far from us, how could anybody
catch it?”

I said, “Dada, how foolish you are!
When mother looks out of her window
and smiles down at us playing, would
you say she’s faraway?”

Still Dada said, “You are a stupid
child! Baby, where could you find
a net big enough to catch the moon?”
I said, “Surely you could catch it with
your hands.”

But Dada laughed and said,
“You are the silliest child I have
known. If it came nearer, you would
see how big the moon is.”

I said, “Dada, what nonsense they teach at
your school! When mother
bends her face down to kiss us, does her face look very big?”
But still Dada says, “You are a stupid child!”

The Astronomer Summary in Malayalam

I only said, ……………….. anybody catch it (Text Book page 932)
ഞാൻ ഇത്രയേ പറഞ്ഞുള്ളൂ, വൈകുന്നേരം ആ ദദം മരത്തിന്റെ കൊമ്പുകൾക്കിടയിൽ ഉരുണ്ട പൂർ ചന്ദ്രൻ കുടുങ്ങിക്കിടക്കുമ്പോൾ (entangled) ആർക്കെങ്കിലും അതിനെ പിടിച്ചെടുക്കാനാവില്ലേ? എന്നാൽ ദാദ എന്നെ നോക്കി ചിരിച്ചുകൊണ്ട് പ റഞ്ഞു, കുഞ്ഞ്, ഞാനറിഞ്ഞതിൽ വെച്ച് ഏറ്റവും വിഡ്ഢിയായ (silliest) കുട്ടിയാണ് നീ. ചന്ദ്രൻ നമ്മളിൽ നിന്ന് ഒരുപാട് ദൂരെയാണ്, ആർക്കെങ്ങനെ അതിനെ പിടിക്കാനാകും?

I said, “Dada………..with your hands” (Text Book Page 92)
ഞാൻ പറഞ്ഞു, ‘ദാദാ, എന്തൊരു വിഡ്ഢിയാണ് (foolish) നിങ്ങൾ! അമ്മ ജനലിലൂടെ പുറത്തേക്ക് നോക്കി നമ്മൾ കളിക്കുന്നത് കണ്ട് പുഞ്ചിരിക്കു മ്പോൾ, അമ്മ ഒരുപാട് ദൂരെയാണെന്ന് (faraway) നിങ്ങൾ പറയുമോ?’

അപ്പോഴും ദാദ പറഞ്ഞു, ‘നീ ഒരു മണ്ടൻ കുട്ടിയാ ണ് കുഞ്ഞ, ചന്ദ്രനെ പിടിക്കാൻ മാത്രം വലിയൊരു വല (net) നിനക്ക് എവിടെനിന്ന് കിട്ടും?’

ഞാൻ പറഞ്ഞു, ‘തീർച്ചയായും നിങ്ങൾക്ക് കൈ കൊണ്ട് അതിനെ പിടിക്കാമല്ലോ.’

But dada laughed …………………….. “You are a studpid child”
എന്നാൽ ദാദ ചിരിച്ചുകൊണ്ട് പറഞ്ഞു, ‘നീയാണ് ഞാനറിഞ്ഞതിൽ വെച്ച് ഏറ്റവും വിഡ്ഢിയായ (silliest) കുട്ടി. അത് അടുത്തേക്ക് വന്നാൽ, ചന്ദ്രൻ എത്ര വലുതാണെന്ന് നിനക്ക് കാണാമായിരുന്നു.’

ഞാൻ പറഞ്ഞു, ‘ദാദാ, നിങ്ങളുടെ സ്കൂളിൽ എന്ത് വിഡ്ഢിത്തമാണ് (nonsense) ഠിപ്പിക്കുന്നത്. അമ്മ നമ്മളെ ഉമ്മ വെക്കാനായി മുഖം താഴേക്ക് കുനിക്കുമ്പോൾ കുനിക്കുമ്പോൾ (bends), അമ്മയുടെ മുഖം വളരെ വലുതായി തോന്നാറുണ്ടോ?’
പക്ഷെ അപ്പോഴും ദാദ പറയുന്നു, ‘നീ ഒരു മണ്ടൻ കുട്ടിയാണ്!’

The Astronomer by Ruskin Bond About the Author

Rabindranath Tagore (1861 – 1941), often referred to as ‘Gurudev’, was a revered Indian poet, artist, musician and philosopher. His collection Gitanjali won him the Nobel Prize for Literature in 1913. Tagore was not only a literary icon, but also a key figure in India’s tight for independence. He is the renowned composer of the national anthems of India, ‘Jana Gana Mana,’ and of Bangladesh, ‘Amar Shonar Bangla.’ His works celebrate the beauty of life, love, and the human spirit.

Parents often use SCERT Kerala Syllabus 8th Standard English Notes Pdf Unit 3 Chapter 2 Engine Trouble Questions and Answers Activities Notes to assist their kids with homework.

Class 8 English Engine Trouble Question Answer Activities

Engine Trouble Questions and Answers Class 8

8th Standard English Engine Trouble Question Answer

Question 1.
Have you ever seen a show such as Gaiety Land? Describe your experience.
ഗേറ്റി ലാൻഡ് പോലുള്ള ഒരു പ്രദർശനം നിങ്ങൾ എപ്പോ ഴെങ്കിലും കണ്ടിട്ടുണ്ടോ? നിങ്ങളുടെ അനുഭവം വിവ രിക്കുക.)
Answer:
Yes, I have seen shows similar to Gaiety Land, during our local temple festival (Utsavam). A large ground is set up with many attractions like giant wheels, merry-go-rounds, and small stalls with games like shooting balloons. There are also magic shows, food stalls, and shops selling toys. The place is always very crowded, noisy, and filled with fun and excitement.

Question 2.
What is a road engine used for?
ഒരു റോഡ് എഞ്ചിൻ എന്തിനാണ് ഉപയോഗിക്കുന്നത്?
Answer:
A road engine, also known as a road roller, is a heavy construction vehicle. It is mainly used to flatten and compact surfaces like soil, gravel, and tar (asphalt) during the construction of roads to make the surface smooth and level.

Question 3.
Why couldn’t the narrator transport the road engine immediately?
എന്തുകൊണ്ടാണ് കഥാനായകന് റോഡ് എഞ്ചിൻ ഉടന ടി കൊണ്ടുപോകാൻ കഴിയാഞ്ഞത്?
Answer:
The narrator couldn’t transport the road engine immediately because it was a very large and heavy machine. It wans’t a small prize that he could simply carry home. He also needed a special driver who knew how to operate it, and he could not find one easily.

Question 4.
How did the temple priest help the narrator?
അമ്പലത്തിലെ പൂജാരി എങ്ങനെയാണ് കഥാനായകനെ സഹായിച്ചത്?
Answer:
The temple priest helped the narrator by offering the services of the temple elephant. The elephant was used to help push and move the huge road engine from the Gymkhana grounds.

Question 5.
What happened when the engine was moved to the road?
എഞ്ചിൻ റോഡിലേക്ക് മാറ്റിയപ്പോൾ എന്ത് സംഭവിച്ചു?
Answer:
When the engine was moved to the road, it went out of control. Instead of going straight, it began to wobble and zig-zag. Finally, it ran straight into the compound wall of a nearby house and destroyed a large part of it.

Question 6.
How did Nature help the narrator solve his problem?
കഥാനായകനെ അവന്റെ പ്രശ്നം പരിഹരിക്കാൻ പ്രക തി എങ്ങനെയാണ് സഹായിച്ചത്?
Answer:
Nature helped the narrator in an unexpected way. An earthquake shook the town, and its tremors caused the road engine to fall into a nearby disused well. The owner of that property was so happy that the dangerous well was finally covered that he promised to pay off all the narrator’s debts, which solved all his problems.

Engine Trouble Class 8 Question Answer – Let’s Rewind

Question 1.
What would you do if you won a road engine in a lottery?
നിങ്ങൾക്ക് ലോട്ടറിയിൽ ഒരു റോഡ് എഞ്ചിൻ സമ്മാന മായി ലഭിച്ചാൽ നിങ്ങൾ എന്ത് ചെയ്യും?
Answer:
If I won a road engine in a lottery, I would be very shocked and confused at first, just like the narrator. After that, I would not try to move it myself. Instead, I would immediately try to find a construction company or someone who deals with heavy machinery and sell it to them for a reasonable price.

Question 2.
Why did the people gaze at the narrator as if he were a strange animal?
എന്തുകൊണ്ടാണ് ആളുകൾ കഥാനായകനെ ഒരു വിചിത്രജീവിയെപ്പോലെ തുറിച്ചുനോക്കിയത്?
Answer:
The people gazed at the narrator as if he were a strange animal because winning a huge, impractical road engine in a lottery is a very unusual and funny situation. They were curious and amused to see the person who was the “lucky” winner of such a trouble some prize.

Question 3.
How do the other characters like Joseph, the temple elephant, and the coolies add to the humour of the story?
ജോസഫ്, അമ്പലത്തിലെ ആന, ചുമട്ടുതൊഴിലാളികൾ തുടങ്ങിയ മറ്റു കഥാപാത്രങ്ങൾ എങ്ങനെയാണ് കഥ യ്ക്ക് നർമ്മം പകരുന്നത്?
Answer:
These characters add humour to the story through their chaotic and uncoordinated efforts to move the engine. Joseph, a dismissed bus driver, agrees to steer the engine without knowing anything about it. The fifty coolies push it in any direction they like. The temple elephant, instead of just helping, gets angry and does more damage. This combination of an unskilled driver, clueless helpers, and an angry elephant creates a completely chaotic and hilarious scene.

Question 4.
How does the narrator’s initial enthusiasm change in the course of time?
കഥാനായകന്റെ ആദ്യത്തെ ആവേശം കാലക്രമേണ എങ്ങനെയാണ് മാറുന്നത്?
Answer:
The narrator’s initial enthusiasm and fondness for the engine quickly change into desperation and frustration. At first, he loves his prize and visits it daily. However, when he starts getting notices from the municipality, has to pay rent, and faces numerous problems trying to move it, he realizes it’s a huge financial burden and a source of constant trouble.

Question 5.
Do you think machines like the road engine have become outdated? Why/ why not?
റോഡ് എഞ്ചിൻ പോലുള്ള യന്ത്രങ്ങൾ കാലഹരണ പെട്ടുവെന്ന് നിങ്ങൾ കരുതുന്നുണ്ടോ? എന്തുകൊണ്ട് / എന്തുകൊണ്ടില്ല?)
Answer:
Yes, the specific type of old, steam-powered road engine described in the story is now outdated. Today, we use modern road rollers that run on diesel engines. These modern machines are much more powerful, efficient, and easier to operate. However, the basic idea of using a heavy roller for road construction is not outdated; the technology has simply evolved and become much better.

Engine Trouble Activities

Class 8 English Engine Trouble Activities Pdf – Let’s recall and recreate:

Activity 1

• Let’s try to draft a humorous instruction manual.
നമുക്ക് നർമ്മം നിറഞ്ഞ ഒരു നിർദ്ദേശ പുസ്തകം തയ്യാറാ ക്കാൻ ശ്രമിക്കാം.
Now, try to prepare a similar instruction manual for operating a mobile phone.
ഇനി, ഒരു മൊബൈൽ ഫോൺ പ്രവർത്തിപ്പിക്കുന്നതിനായി സമാനമായ ഒരു നിർദ്ദേശ പുസ്തകം തയ്യാറാക്കുക.
Answer:
Instruction Manual: Your New Magical
Rectangle (Mobile Phone)
Step 1: Waking Up the Device

1. Finding the Power Button: This mysterious button is often hiding on the side. Press it getly. If nothing happens, you’ve probably been holding it upside down.
2. Unlocking the Screen: Swipe your finger across the screen with the grace of a ballet dancer. If it asks for a password, try to remember the name of your first pet or ‘1234’.

Step 2: Making a Call

1. Finding the Phone Icon: Look for a small green icon that looks like an old-fashioned telephone. Tap it. Don’t be shy.
2. Talking: Hold the phone to your ear, not your forehead. Shouting does not improve the signal.

Troubleshooting Common Problems

1. App not working: Have you tried turning it off and on again? This is the secret solution to 99% of tech problems.
2. Slow Internet: Walk around the room holding the phone up in the air. This makes the Wi-Fi spirits happy.
3. Low Battery: This is the phone’s way of telling you it needs a nap. Find its favourite snack (the charger) and plug it in.

Maintenance Tips

1. Cleaning the Screen: Use a soft cloth. Using your T-shirt is acceptable only in emergencies.
2. Software Updates: When it asks to update, just say yes. Think of it as the phone going to the gym to get stronger.

Std 8 English Engine Trouble Question Answer – Activity 2

Write a news article, reporting the chaos that erupted when the narrator attempted to move the road engine.
കഥാനായകൻ റോഡ് എഞ്ചിൻ മാറ്റാൻ ശ്രമിച്ചപ്പോൾ ഉണ്ടായ കോലാഹലത്തെക്കുറിച്ച് ഒരു പത്രവാർത്ത തയ്യാറാക്കുക.
Answer:
Lottery Prize Causes Pandemonium in Malgudi; Road Engine Runs Amok
Staff Reporter Malgudil, June 17: A scene of utter chaos erupted in town yesterday when a local man’s attempt to move his lottery prize-a giant road engine-resulted in the destruction of a compound wall near the Gymkhana grounds.

The prize-winner, a resident of Malgudi, had won the massive engine at the Gaiety Land fair. To move his unusual prize, he hired a temple elephant, fifty coolies, and an inexperienced driver. According to witnesses, the ambitious operation went terribly wrong as soon as the engine reached the main road.

The engine, with the elephant yoked to it and the men pushing from behind, went out of control. Instead of moving straight, it wobbled and ran directly into a nearby compound wall, pulverizing a large section of it. The situation worsened when the agitated elephant broke its ropes and caused further damage. The crowd created a pandemonium, and local police had to intervene to control the situation. The incident has left the town buzzing and the road engine stranded, raising questions about the unusual prizes offered at the fair.

Std 8 English Engine Trouble Question Answer – Let’s perform:

Activity 1

Artificial Intelligence (AI) and Human Stupidity
– Yuval Noah Harari
I believe that at least in the next few decades, we wouldn’t need to worry about robots taking over the world. While we will use computers to help us make decisions, these computers won’t have feelings or consciousness.

Modern science fiction sometimes mixes up intelligence (the ability to solve problems) with consciousness (the ability to feel emotions). In movies, a robot might become conscious and try to destroy humans or fall in love with them. But in real life, there is no reason to believe that computers will develop feelings. For example, airplanes fly faster than birds, without feathers, and computers solve problems, without feelings or emotions.

The real danger is not robots taking over but rather that AI might be used to manipulate people’s emotions, convincing someone to buy something or support a certain idea. This is already happening, where data from social media influences voters in elections or consumers in the market.

If we’re not careful, we might end up with people who misuse powerful computers in ways that harm themselves and others. It’s important to remember that while technology can be helpful, we must also work on becoming better, more thoughtful humans.

A. Let’s analyse the above passage. The following questions might help you.
മുകളിലെ ഖണ്ഡിക വിശകലനം ചെയ്യാം. താഴെ പറയുന്ന ചോദ്യങ്ങൾ നിങ്ങളെ സഹായിച്ചേക്കാം (Text Book page 90)
• How do you think technology is going to change the world?
സാങ്കേതികവിദ്യ എങ്ങനെയാണ് ലോകത്തെ മാറ്റാൻ പോ കുന്നതെന്ന് നിങ്ങൾ കരുതുന്നു?
Answer:
According to the passage, technology will change the world by helping us make decisions. However, the author warns that it also has a dangerous side, where Artificial Intelligence (Al) can be used to manipulate people’s emotions to influence their buying habits or their votes in elections.

• Will computers develop feelings? Why/ why not?
കമ്പ്യൂട്ടറുകൾക്ക് വികാരങ്ങൾ ഉണ്ടാകുമോ? എന്തുകൊ ണ്ട്/എന്തുകൊണ്ടില്ല?
Answer:
No, according to the author, computers will not develop feelings. He explains that intelligence (the ability to solve problems) is different from consciousness (the ability to feel emotions). He says that just like an airplane can fly without having feathers, a computer can solve problems without having feelings.

• How is Al used to manipulate people’s emotions?
ആളുകളുടെ വികാരങ്ങളെ സ്വാധീനിക്കാൻ Al എങ്ങനെയാണ് ഉപയോഗിക്കുന്നത്?
Answer:
Al is used to manipulate people by analyzing the huge amount of data it collects from our social media activities. This data helps Al understand our likes, dislikes, and fears. It can then show us targeted advertisements and messages that are specifically designed to influence our feelings and convince us to buy something or support an idea.

• Are we relying too much on technology? Why?
നമ്മൾ സാങ്കേതികവിദ്യയെ അമിതമായി ആശ്രയിക്കു ന്നുണ്ടോ? എന്തുകൊണ്ട്?
Answer:
Yes, it seems we are beginning to rely too much on technology. The passage suggests that we are already letting technology influence our important decisions, like who to vote for. This over-reliance is risky because, as the author says, it can make us easy to manipulate.

• How can we retain our humanity in this era of evolving technology?
കാലഘട്ടത്തിൽ നമുക്ക് എങ്ങനെ നമ്മുടെ മനുഷ്യത്വം നിലനിർത്താനാകും?
Answer:
We can retain our humanity by remembering that technology is just a tool to help us. The author suggests that we must focus on becoming “better, more thoughtful humans.” This means we must be careful and responsible about how we use technology and always prioritize human values like kindness and care.

B. Now, let’s conduct a debate in the class on the topic ‘Use of Technology; a Boon or a Bane’? You can form two groups. Each group may seek to justify one aspect of the topic. One person could take the role of ‘moderator’ to facilitate the debate.

• Let’s list the points for Group A and Group B.

You may use the following expressions in the course of the debate.
• Welcome, everyone, to today’s debate on…
• From our perspective…
• Evidence suggests that…
• We disagree with that point because…
• We need to stay within the allotted time.
• Our position is that…
• While that may be true, it’s also important to note…
• Please allow the speaker to finish.
• I strongly support that…
• ………………………………………
• ……………………………………………
• ……………………………………………..
Answer:

• Let’s list the points for Group A and Group B.

Benefit	Harmful effect
• Increased efficiency and productivity	• Job displacement and unemployment
• Easy access to information and education	• Addiction and excessive screen time
• Improved communication and connectivity	• Spread of misinformation and fake news
• Advancements in medicine and healthcare	• Privacy concerns and misuse of personal data

Engine Trouble Class 8 Question Answer – Activity 2

The narrator tries to convince the municipal chairman to buy the road engine. Now, let’s enact the scene after preparing a script.
കഥാനായകൻ മുനിസിപ്പൽ ചെയർമാനെ റോഡ് എഞ്ചിൻ വാങ്ങാൻ പ്രേരിപ്പിക്കാൻ ശ്രമിക്കുന്നു. ഇനി, ഒരു തിരക്കഥ തയ്യാറാക്കി ആ രംഗം അഭിനയിക്കാം.
A Scene at the Municipal Office
Characters:
• Narrator,
• Municipal Chairman
(Setting: The Chairman’s office. The Chairman is looking at some files on his desk. The Narrator enters the room nervously.)
Answer:
Narrator: Good morning, sir. Excuse me for disturbing you.
Chairman: (Looks up from his file, looking busy) Yes? What is it?
Narrator: Sir, I am here with a wonderful opportunity for our municipality. An asset that could change the face of our roads!
Chairman: (Leaning back in his chair, slightly amused) An opportunity? An asset? What are you talking about, young man?
Narrator: A road engine, sir! A fine, strong road engine! I won it in a lottery at the Gaiety Land fair. I know the municipality is always working hard to improve our roads. If you buy this engine, you will save a lot of money!
Chairman: (Starts laughing) You won a road engine? At that fair? Son, I have enough trouble with the roads as it is. I don’t need the trouble of owning a second-hand engine.
Narrator: But sir, I am prepared to give it away at a great concession! A very low price! Think of the importance of owning a road roller!
Chairman: (Stands up) I have a lot of work to do. Thank you for your interesting offer, but we are not interested. Good day.
(The Narrator looks very disappointed and slowly walks out of the room.)

Students often refer to Kerala Syllabus 8th Standard English Textbook Answers and Engine Trouble in Malayalam & English before discussing the text in class.

Class 8 English Engine Trouble Summary

Engine Trouble Summary in English

There came to our town some years ago a showman who owned an institution called Gaiety Land. Crowds poured into the show from all over the district. Within a week of opening, they collected nearly five hundred rupees a day in gate money alone.

Gaiety Land provided us with all sorts of fun and gambling and side-shows. For a couple of annas we could watch anything in any booth — from performing parrots to crack motorcyclists looping the Dome of Death. There were lotteries and shooting galleries. Here, for just eight annas you could acquire prizes that ranged from pincushions, sewing machines, cameras to even a road engine.

One evening they drew the ticket number 1005, and I happened to own it. Glancing down the list, they declared that I had become the owner of the road engine! Don’t ask me how a road engine came to be included among the prizes. I was stunned. People gathered around and gazed at me as if I were a strange animal. It was not the sort of prize one could carry home at short notice.

I asked the showman if he would help me to transport it. He declined but agreed to keep the engine on the My words grounds till the end of their season.

I asked the showman if he could find me a driver. He just smiled.
“Can’t I sell it to some municipality?” I asked innocently.

He burst into a laugh. “As a showman I have enough trouble with municipal people. I would rather keep out of their way.” My friends and well-wishers poured in to congratulate me on my latest acquisition.

Every day I made a trip to the Gymkhana grounds to have a look at my engine. I grew very fond of it. I loved its shining brass parts. I stood near it and patted it affectionately, hovered about it, and returned home every day only at the close of the show.

When the showman finally packed up, I received a notice from the municipality to collect my road engine. When I went there the next day, it looked neglected. The showman had moved on, leaving the engine where it stood. It was perfectly safe, though.

Soon I received a second notice from the municipality ordering that the engine should be removed with immediate effect. Otherwise, they would charge rent for the grounds. After deep thought I consented to pay the rent. I paid ten rupees a month for the next three months.

Dear sirs, I was a poor man. Even the house which my wife and I occupied cost me only four rupees a month. And fancy my paying ten rupees a month for the road engine. It cut into my slender budget, and I had to pledge a jewel or two belonging to my wife! Every day my wife asked me what I proposed to do with the engine. I had no answer to give her. I went up and down the town offering it for sale to all and sundry.

Someone suggested, “Meet the Municipal Chairman. He may buy it for the municipality.” With great apprehension I went to the municipal office and entered the Chairman’s room. I mentioned my business. I told him I was prepared to give away the engine at a great concession. I started talking about the importance of owning a road roller, but that attempt too turned out to be futile.

I realised that I was making myself bankrupt maintaining the engine in the Gymkhana grounds. Fresh complications arose when a cattle show came, and I was given twenty-four hours to get the thing out of the grounds. I became desperate; there was not a single person for fifty miles around who knew anything about driving a road engine. I begged every passing bus driver to help me: but without use. I even approached the station master to put in a word with the mail engine driver.

Meanwhile the municipality was pressing me to clear out. I saw the priest of the local temple and managed to gain his sympathy. He offered me the services of his temple elephant. I also engaged fifty coolies to push the engine from behind. You may be sure this drained all my resources. The coolies wanted eight annas per head, and the temple elephant cost me seven rupees a day and I had to give it a day’s feed.

My plan was to take the engine out of the Gymkhana and then down the road to a field that was owned by a friend. I also took into service one Joseph, a dismissed bus-driver. Joseph said that although he knew nothing of road-rollers he could nevertheless steer one if it was somehow kept in motion. It was a fine sight: the temple elephant yoked to the engine by means of stout ropes, with fifty determined men pushing it from behind, and my friend Joseph sitting in the driving seat.

A huge crowd stood around and watched in great glee. The engine began to move. It seemed to me the greatest moment in my life. When it came out of the Gymkhana to the main road, the engine began to behave in a strange manner. Instead of going straight down the road, it began to wobble and zig-zag.

The elephant dragged it one way; Joseph turned the wheel without any idea of where he was going. The fifty men behind it clung to it and pushed it just where they liked. As a result of all this confused dragging, the engine ran straight into the wall of the opposite compound and reduced a good length of it to powder. At this the crowd let out a joyous yell.

The elephant, disliking the behaviour of the crowd, trumpeted loudly. It strained and snapped its ropes and kicked down a further length of the wall. The fifty men fled in panic; the crowd created a pandemonium. Someone slapped me in the face: it was the owner of the compound wall. The police came on the scene and marched me off.

When I was released from the lock-up I found the following consequences awaiting me:
(1) Several yards of compound wall had to be built by me:
(2) The wages of the fifty men who ran away had to be paid. They would not explain how they were entitled to the wages when they had not done their job.
(3) Joseph’s fee for steering the engine over the wall had to be paid.
(4) The medicine bill for the temple elephant’s injuries while kicking down the wall had to be paid. Here again the temple authorities would not listen when I pointed out that I didn’t engage the elephant to break down the wall.
(5) Last, but not least, the demand to move the engine out of its present station.

I was at a loss. What could I do? I had no more money to spend, and my wife refused to part with her thali, the last of her jewels.

However, Nature came to my rescue in an unexpected manner. You may have heard of the earthquake of that year which destroyed whole towns in Northern India.
There was a reverberation of it in our town, too. We were thrown out of our beds that night, and doors and windows rattled.

Next morning I went over to take a last look at my engine before leaving the town. I could hardly believe my eyes. The engine was not there. I looked about and raised a hue and cry. Search parties went round. The engine was found in a disused well nearby, with its back up! The owner of the property was so pleased the well was covered at last that he promised to pay off all my debts. He even offered me some money in further payment which I refused to accept.
(Adapted)

Engine Trouble Summary in Malayalam

There came to our ………………. to even a road engine (Text book Page 83)
ഏതാനും വർഷങ്ങൾക്കുമുൻപ്, ഗേറ്റി ലാൻഡ് എന്ന പേരിൽ ഒരു സ്ഥാപനം (institution) നടത്തിയി രുന്ന ഒരു പ്രദർശനക്കാരൻ (showman) ഞങ്ങളു ടെ പട്ടണത്തിൽ വന്നു. ജില്ലയുടെ (district) എല്ലാ ഭാഗത്തുനിന്നും ആൾക്കൂട്ടങ്ങൾ ആ പ്രദർശനത്തി ലേക്ക് ഒഴുകിയെത്തി (poured into). ആരംഭിച്ച് ഒരാഴ്ചയ്ക്കുള്ളിൽ, പ്രവേശന ഫീസായി (gate money) മാത്രം അവർക്ക് ഒരു ദിവസം ഏകദേശം അഞ്ഞൂറ് രൂപ ലഭിച്ചു.

ഗേറ്റി ലാൻഡ് ഞങ്ങൾക്ക് പലതരം വിനോദങ്ങളും, ചൂതാട്ടവും (gambling), ചെറിയ പ്രദർശനങ്ങളും (side-shows) നൽകി (provided). ഏതാനും അണകൾക്ക് ഏത് കൂടാരത്തിലും (booth)എന്ത്വേ ണമെങ്കിലും കാണാമായിരുന്നു അഭ്യാസം കാണി ക്കുന്ന തത്തകൾ മുതൽ മരണക്കിണറിൽ (Dome of Death) വട്ടംകറങ്ങുന്ന (looping) വിദഗ്ദ്ധ രായ മോട്ടോർസൈക്കിൾ അഭ്യാസികളെ (crack motorcyclists) വരെ. അവിടെ ലോട്ടറികളും (lotteries) ഷൂട്ടിംഗ് ഗാലറി കളും (shooting galleries) ഉണ്ടായിരുന്നു. വെറും എട്ട് അണയ്ക്ക്, പിൻ കുഷ്യനുകൾ (pincushions), തയ്യൽ യന്ത്രങ്ങൾ (sewing machines),ക്യാമറകൾ തുടങ്ങി ഒരു റോഡ് റോളർ (road engine) വരെ വ്യാപിച്ചുകിടക്കുന്ന (ranged from) സമ്മാനങ്ങൾ നേടാമായിരുന്നു (acquire).

One evening they ………………… next three months (Text Book Page 84)
ഒരു വൈകുന്നേരം അവർ 1005 എന്ന ടിക്കറ്റ് നമ്പർ നറുക്കെടുത്തു (drew), അതെന്റേതായി (happened to own it). പട്ടികയിലൂടെ ഓടിക്കണ്ണോടിച്ചപ്പോൾ (Glancing), ഞാൻ റോഡ് എഞ്ചിന്റെ ഉടമയായെന്ന് അവർ പ്രഖ്യാപിച്ചു (declared)! എങ്ങനെയാണ് ഒരു റോഡ് എഞ്ചിൻ സമ്മാനങ്ങളുടെ കൂട്ടത്തിൽ വന്നതെന്ന് എന്നോട് ചോദിക്കരുത്. ഞാൻ സ്തബ്ദ നായിപ്പോയി (stunned). ഞാനൊരു വിചിത്രജീവി യാണെന്ന മട്ടിൽ ആളുകൾ എന്റെ ചുറ്റുംകൂടി എന്നെ തുറിച്ചുനോക്കി (gazed at me). ചുരുങ്ങി യ സമയത്തിനുള്ളിൽ (at short notice) വീട്ടിലേക്ക് കൊണ്ടുപോകാൻ കഴിയുന്ന തരത്തിലുള്ള ഒരു സമ്മാനമായിരുന്നില്ല അത്. അത് കൊണ്ടുപോകാൻ (transport) സഹായിക്കാമോ എന്ന് ഞാൻ പ്രദർ ശനക്കാരനോട് ചോദിച്ചു. അദ്ദേഹം നിരസിച്ചു (declined), പക്ഷെ അവരുടെ പ്രദർശന കാലാവധി (season) തീരുന്നതുവരെ എഞ്ചിൻ ആ മൈതാ നത്ത് സൂക്ഷിക്കാൻ സമ്മതിച്ചു. എനിക്കൊരു ഡ്രൈവറെ കണ്ടെത്താമോ എന്നും ഞാൻ ചോദിച്ചു. അയാൾ വെറുതെ പുഞ്ചിരിച്ചു.

എനിക്കിത് ഏതെങ്കിലും നഗരസഭയ്ക്ക്(municipality) വിൽക്കാൻ കഴിയില്ലേ? ഞാൻ നിഷ്കളങ്കമായി (innocently) ചോദിച്ചു. അയാൾ പൊട്ടിച്ചിരിച്ചു (burst into a laugh), ഒരു പ്രദർശനക്കാരൻ എന്ന നിലയിൽ എനിക്ക് നഗരസഭക്കാരെക്കൊണ്ട് ആവശ്യ ത്തിന് പൊല്ലാപ്പുണ്ട്. ഞാൻ അവരുടെ വഴിക്ക് പോകാ തിരിക്കുന്നതാണ് നല്ലത്. എന്റെ ഏറ്റവും പുതിയ നേട്ടത്തിൽ (acquisition) എന്നെ അഭിനന്ദിക്കാൻ എന്റെ സുഹൃത്തുക്കളും അഭ്യുദയകാംക്ഷികളും (well-wishers) ഒഴുകിയെത്തി. എല്ലാ ദിവസവും ഞാൻ ജിംഖാന മൈതാനത്തേക്ക് എന്റെ എഞ്ചിൻ കാണാനായി ഒരു യാത്ര നടത്തി. എനിക്കതിനോട് വലിയ ഇഷ്ടം തോന്നി (grew very fond of it). അതി ന്റെ തിളങ്ങുന്ന പിച്ചള ഭാഗങ്ങൾ ഞാൻ സ്നേഹിച്ചു.

ഞാനതിനരികെ നിന്ന് വാത്സല്യത്തോടെ (affectionately) തലോടി, അതിന്റെ ചുറ്റും ചുറ്റിപ്പറ്റി നിന്നു (hovered about it), പ്രദർശനം തീരു മ്പോൾ മാത്രം എല്ലാ ദിവസവും വീട്ടിലേക്ക് മടങ്ങി. പ്രദർശനക്കാരൻ ഒടുവിൽ സാധനങ്ങൾ കെട്ടിപ്പെ റുക്കി പോയപ്പോൾ (packed up), എന്റെ റോഡ് എഞ്ചിൻ അവിടെനിന്ന് എടുത്തുകൊണ്ടുപോ കാൻ നഗരസഭയിൽ നിന്ന് എനിക്കൊരു നോട്ടീസ് ലഭിച്ചു. അടുത്ത ദിവസം ഞാൻ അവിടെ ചെന്ന പ്പോൾ അത് അവഗണിക്കപ്പെട്ട (neglected) നില യിൽ കാണപ്പെട്ടു. പ്രദർശനക്കാരൻ പോയിക്കഴി ഞ്ഞിരുന്നു, എഞ്ചിൻ നിന്നയിടത്ത് ഉപേക്ഷിച്ചു കൊണ്ട്. പക്ഷെ അത് പൂർണ്ണമായും സുരക്ഷിത മായിരുന്നു.

താമസിയാതെ, എഞ്ചിൻ ഉടനടി പ്രാബല്യത്തിൽ (with immediate effect) അവിടെനിന്ന് നീക്കം
ചെയ്യണമെന്ന് (removed) ആവശ്യപ്പെട്ട് നഗരസഭ യിൽ നിന്ന് എനിക്ക് രണ്ടാമത്തെ നോട്ടീസ് ലഭിച്ചു. അല്ലാത്തപക്ഷം, അവർ ആ സ്ഥലത്തിന് വാടക ഈടാക്കുമെന്ന് (charge rent) പറഞ്ഞു. ദീർഘ മായ ആലോചനയ്ക്ക് ശേഷം ഞാൻ വാടക നൽ കാൻ സമ്മതിച്ചു (consented), അടുത്ത മൂന്നു മാസത്തേക്ക് ഞാൻ മാസം പത്തുരൂപ വീതം അടച്ചു.

Dear sir I was ……………… mail engne driver (Text Book Page 85)
പ്രിയപ്പെട്ടവരേ, ഞാനൊരു പാവപ്പെട്ടവനായിരുന്നു. ഞാനും ഭാര്യയും താമസിച്ചിരുന്ന (occupied) വീടിന് പോലും എനിക്ക് മാസം നാല് രൂപയേ ചെലവുണ്ടായിരുന്നുള്ളൂ. ആ റോഡ് എഞ്ചിനു വേണ്ടി ഞാൻ മാസം പത്തുരൂപ കൊടുക്കുന്നത് ഒന്ന് സങ്കൽപ്പിച്ചുനോക്കൂ (fancy)! അത് എന്റെ ചുരുങ്ങിയ ബഡ്ജറ്റിൽ (slender budget) വലി യൊരു പങ്കെടുത്തു, എന്റെ ഭാര്യയുടെ ഒന്നോ രണ്ടോ ആഭരണങ്ങൾ എനിക്ക് പണയം വെക്കേണ്ടി (pledge) വന്നു! എല്ലാ ദിവസവും എന്റെ ഭാര്യ ആ എഞ്ചിൻ കൊണ്ട് ഞാനെന്താണ് ഉദ്ദേശിക്കു ന്നതെന്ന് (proposed) ചോദിക്കും. എനിക്കവൾക്ക് നൽകാൻ ഉത്തരമൊന്നുമുണ്ടായിരുന്നില്ല.

ഞാൻ പട്ടണത്തിൽ അങ്ങോട്ടുമിങ്ങോട്ടും നടന്ന് കണ്ട വരോടെല്ലാം (all and sundry) അത് വിൽപ്പ നയ്ക്ക് വെച്ചു. ആരോ നിർദ്ദേശിച്ചു (suggested), മുനിസിപ്പൽ ചെയർമാനെ കാണൂ. ഒരുപ ക്ഷേ അദ്ദേഹം അത് മുനിസിപ്പാലിറ്റിക്ക് വേണ്ടി വാങ്ങിയേക്കാം. വലിയ ആശങ്കയോടെ (apprehension) ഞാൻ മുനിസിപ്പൽ ഓഫീസിൽ പോയി ചെയർമാന്റെ മുറിയിൽ പ്രവേശിച്ചു. ഞാൻ എന്റെ കാര്യം പറഞ്ഞു. വലിയ വിലക്കിഴിവിൽ (conces sion) എഞ്ചിൻ നൽകാൻ ഞാൻ തയ്യാറാണെന്ന് ഞാൻ അദ്ദേഹത്തോട് പറഞ്ഞു. ഒരു റോഡ് റോ ളർ സ്വന്തമാക്കുന്നതിന്റെ പ്രാധാന്യത്തെക്കുറിച്ച് ഞാൻ സംസാരിക്കാൻ തുടങ്ങി, എന്നാൽ ആ ശ്രമവും വിഫലമായി (futile).

ജിംഖാന മൈതാനത്ത് എഞ്ചിൻ പരിപാലിച്ച് ഞാൻ പാപ്പരാവുകയായിരുന്നു (bankrupt) എന്ന് ഞാൻ തിരിച്ചറിഞ്ഞു. അവിടെ ഒരു കന്നുകാലി പ ദർശനം വന്നപ്പോൾ പുതിയ പ്രശ്നങ്ങൾ (compli cations) ഉണ്ടായി, ഇരുപത്തിനാല് മണിക്കൂറിനു ള്ളിൽ ആ സാധനം മൈതാനത്തുനിന്ന് മാറ്റാൻ എനിക്ക് നിർദ്ദേശം ലഭിച്ചു. ഞാൻ നിസ്സഹായനാ യി (desperate); അൻപത് മൈൽ ചുറ്റളവിൽ ഒരു റോഡ് എഞ്ചിൻ ഓടിക്കുന്നതിനെക്കുറിച്ച് അറി യാവുന്ന ഒരാൾ പോലും ഉണ്ടായിരുന്നില്ല. അതു വഴി പോയ എല്ലാ ബസ് ഡ്രൈവർമാരോടും ഞാൻ സഹായത്തിനായി യാചിച്ചു. പക്ഷെ ഒരു പ്രയോജ നവുമുണ്ടായില്ല. മെയിൽ എഞ്ചിൻ ഡ്രൈവറോട് ഒരു വാക്ക് പറയാൻ (put in a word) ഞാൻ സ്റ്റേ ഷൻ മാസ്റ്ററെ പോലും സമീപിച്ചു (approached).

Meanwhile the municipality ……………… wobble and zig-zag(Text Book Page 85, 86)
അതേസമയം, സ്ഥലം ഒഴിയാൻ മുനിസിപ്പാലിറ്റി എന്നെ നിർബന്ധിച്ചുകൊണ്ടിരുന്നു (pressing me). ഞാൻ അടുത്തുള്ള അമ്പലത്തിലെ പൂജാരി യെ കണ്ട് അദ്ദേഹത്തിന്റെ സഹതാപം നേടാൻ (gain his sympathy) എനിക്ക് കഴിഞ്ഞു. അദ്ദേഹം തന്റെ അമ്പലത്തിലെ ആനയുടെ സേവനം എനിക്ക് വാഗ്ദാനം ചെയ്തു. എഞ്ചിൻ പിന്നിൽ നിന്ന് തള്ളാനാ യി ഞാൻ അൻപത്ചു മട്ടുതൊഴിലാളികളെയും (coolies) ഏർപ്പാടാക്കി (engaged). ഇതെന്റെ സമ്പാദ്യം മുഴുവൻ കാലിയാക്കി (drained all my resources) എന്ന് നിങ്ങൾക്ക് ഉറപ്പിക്കാം. ചുമട്ടുതൊഴിലാളികൾക്ക് ഒരാൾക്ക് എട്ട് അണയും, അമ്പലത്തിലെ ആനയ്ക്ക് ഒരു ദിവസം ഏഴ് രൂപയും, അതിന് ഒരു ദിവസത്തെ തീറ്റയും എനിക്ക് നൽ കേണ്ടിവന്നു. ജിംഖാനയിൽ നിന്ന് എഞ്ചിൻ പുറത്തെടുത്ത് ഒരു സുഹൃത്തിന്റേതായ വയലി ലേക്ക് റോഡിലൂടെ കൊണ്ടുപോകാനായിരുന്നു എന്റെ പദ്ധതി. പിരിച്ചുവിട്ട (dismissed) ഒരു ബസ് ഡ്രൈവറായ ജോസഫിനെയും ഞാൻ ജോലിക്ക് വെച്ചു.

റോഡ് റോളറുകളെക്കുറിച്ച് ഒന്നും അറിയില്ലെങ്കിലും, അത് ഓടുകയാണെങ്കിൽ തനിക്ക് നിയന്ത്രിക്കാൻ (steer) കഴിയുമെന്ന് (nevertheless) ജോസഫ് പറഞ്ഞു. എങ്ങനെയോ ചലിപ്പിച്ചു (kept in motion). അതൊരു നല്ല കാഴ്ചയായിരുന്നു (fine sight): അമ്പലത്തിലെ ആനയെ ഉറപ്പുള്ള കയറു കൾ (stout ropes) കൊണ്ട് എഞ്ചിനുമായി കെട്ടി യിട്ടിരിക്കുന്നു (yoked), ദൃഢനിശ്ചയമുള്ള (determined) അൻപത് പേർ പിന്നിൽ നിന്ന് തള്ളുന്നു, എന്റെ സുഹൃത്ത് ജോസഫ് ഡ്രൈവിംഗ് സീറ്റിലി രിക്കുന്നു. വലിയൊരു ജനക്കൂട്ടം ചുറ്റും നിന്ന് വലിയ ആഹ്ലാദത്തോടെ (glee) അത് കണ്ടു. എഞ്ചിൻ ചലി ക്കാൻ തുടങ്ങി. എന്റെ ജീവിതത്തിലെ ഏറ്റവും വലിയ നിമിഷമായി (greatest moment) എനിക്കത് തോന്നി. അത് ജിംഖാനയിൽ നിന്ന് പ്രധാന റോഡിലേക്ക് വന്നപ്പോൾ, എഞ്ചിൻ വിചിത്രമായി പെരുമാറാൻ തുടങ്ങി. നേരെ പോകുന്നതിന് പകരം, അത് ആടിയുലയാനും (wobble) വളഞ്ഞുപുളഞ്ഞു പോകാനും (zig-zag) തുടങ്ങി.

The elephant dragged …………….. its present station
ആന അതിനെ ഒരു വശത്തേക്ക് വലിച്ചു (dragged); താനെങ്ങോട്ടാണ് പോകുന്നതെന്നറിയാതെ ജോസ ഫ് സ്റ്റിയറിംഗ് തിരിച്ചു. പിന്നിലുണ്ടായിരുന്ന അൻ പത് പേർ അതിനെ അള്ളിപ്പിടിച്ച് (clung to it) അവ ർക്കിഷ്ടമുള്ളിടത്തേക്ക് തള്ളി. ഈ ആശയക്കുഴപ്പം നിറഞ്ഞ (confused) വലിച്ചുനീട്ടലിന്റെ ഫലമായി, എഞ്ചിൻ നേരെ എതിർവശത്തുള്ള കോമ്പൗണ്ടിന്റെ മതിലിലേക്ക് ഇടിച്ചുകയറി അതിന്റെ നല്ലൊരു ഭാഗം ഇടിച്ച് പൊടിയാക്കി (reduced to powder). ഇതു കണ്ട് ജനക്കൂട്ടം സന്തോഷത്തോടെ അലറിവിളിച്ചു (joyous yell). ജനക്കൂട്ട ത്തിന്റെ പെരുമാറ്റം ഇഷ്ടപ്പെടാതെ (disliking) ആന ഉച്ചത്തിൽ ചിന്നംവിളിച്ചു (trumpeted).അത്ആഞ്ഞു(strained) കയറുകൾ പൊട്ടിക്കുകയും (nsapped its ropes) മതിലിന്റെ കൂടുതൽ ഭാഗം ചവിട്ടിപ്പൊളിക്കുകയും ചെയ്തു. അൻപത്പേരും ഭയന്ന് ഓടി (fled in panic); ജനക്കൂട്ടം ഒരു ബഹളമയമായ (pandemonium) അന്തരീക്ഷം സൃ ഷ്ടിച്ചു. ആരോ എന്റെ മുഖത്തടിച്ചു. അത് ആ കോമ്പൗണ്ട് മതിലിന്റെ ഉടമയായിരുന്നു. പോ ലീസ് സംഭവസ്ഥലത്തെത്തി എന്നെ കൊണ്ടുപോ യി (marchedme off) ലോക്കപ്പിൽ lock-up) നിന്ന് പുറത്തിറങ്ങിയപ്പോൾ, താഴെ പറയുന്ന അനന്തരഫല ങ്ങൾ (consequences) എന്നെ കാത്തിരിക്കുന്നത് ഞാൻ കണ്ടു:

1. നിരവധി മുറ്റങ്ങളുടെ കോമ്പൗണ്ട് മതിൽ ഞാൻ പ ണിതുകൊടുക്കണം.
2. ഓടിപ്പോയ അൻപത് പേരുടെ കൂലി (wages) കൊടുക്കണം. ജോലി ചെയ്യാതിരുന്നിട്ടും അവർക്കെ ങ്ങനെ കൂലിക്ക് അർഹതയുണ്ടായി (entitled) എന്ന് അവർ വിശദീകരിക്കില്ലായിരുന്നു.
3. മതിൽപ്പുറത്തുകൂടി എഞ്ചിൻ ഓടിച്ചതിന് ജോസ ഫിന്റെ ഫീസ് കൊടുക്കണം.
4. മതിൽ ചവിട്ടിപ്പൊളിച്ചപ്പോൾ അമ്പലത്തിലെ ആന യ്ക്കുണ്ടായ പരിക്കിനുള്ള മരുന്നിന്റെ ബിൽ കൊടു ക്കണം. ആനയെ മതിൽ പൊളിക്കാൻ ഏർപ്പാടാക്കിയ തല്ലെന്ന് ഞാൻ ചൂണ്ടിക്കാണിച്ചപ്പോൾ അമ്പലം അധി കാരികൾ കേൾക്കാൻ തയ്യാറായില്ല.
5. അവസാനമായി, എഞ്ചിൻ അതിന്റെ ഇപ്പോഴത്തെ സ്ഥാനത്തുനിന്ന് മാറ്റണമെന്ന ആവശ്യം.

I was at a loss ……………….. refised to accept (Text Book Page 87)
ഞാനാകെ എന്തുചെയ്യണമെന്നറിയാത്ത അവസ്ഥ യിലായി (at a loss). ഞാനെന്തു ചെയ്യും? എന്റെ കയ്യിൽ ചെലവാക്കാൻ പണമില്ല, എന്റെ ഭാര്യ അവ ളുടെ അവസാനത്തെ ആഭരണമായ താലിമാല (thali) വിട്ടുനൽകാനും (part with) വിസമ്മതിച്ചു. എന്നാൽ, അപ്രതീക്ഷിതമായ രീതിയിൽ (unexpected manner) പ്രകൃതി എന്റെ രക്ഷയ്ക്കെത്തി (rescue). ആ വർഷം ഉത്തരേന്ത്യയിലെ പട്ടണങ്ങ ളെ മുഴുവൻ നശിപ്പിച്ച (destroyed) ഭൂകമ്പത്തെ ക്കുറിച്ച് (earthquake) നിങ്ങൾ കേട്ടിട്ടുണ്ടാകും. അതിന്റെ ഒരു പ്രകമ്പനം (reverberation) ഞങ്ങ ളുടെ പട്ടണത്തിലുമുണ്ടായി. ആ രാത്രി ഞങ്ങൾ കട്ടിലിൽ നിന്ന് പുറത്തേക്ക് തെറിച്ചുപോയി, വാതി ലുകളും ജനലുകളും കിരുകിരു ശബ്ദമുണ്ടാക്കി (rattled).

അടുത്ത ദിവസം രാവിലെ പട്ടണം വിടുന്ന തിന് മുൻപ് എന്റെ എഞ്ചിൻ അവസാനമായി ഒന്ന് കാണാൻ ഞാൻ പോയി. എനിക്കെന്റെ കണ്ണുകളെ വിശ്വസിക്കാൻ കഴിഞ്ഞില്ല (hardly believe my eyes). എഞ്ചിൻ അവിടെയുണ്ടായിരുന്നില്ല. ഞാൻ ചുറ്റും നോക്കി ബഹളമുണ്ടാക്കി (raised a hue and cry). തിരച്ചിൽ സംഘങ്ങൾ (Search parties) എല്ലായിടത്തും പോയി. എഞ്ചിൻ അടുത്തു ള്ള ഉപയോഗശൂന്യമായ ഒരു കിണറ്റിൽ (dis used well) നിന്ന് കണ്ടെത്തി, അതിന്റെ പിൻഭാഗം മുകളിലായി. ആ കിണർ ഒടുവിൽ മൂടിയതിൽ ആ സ്ഥലത്തിന്റെ ഉടമസ്ഥൻ വളരെ സന്തുഷ്ടനാ യി (pleased), അദ്ദേഹം എന്റെ എല്ലാ കടങ്ങളും (debts) വീട്ടാമെന്ന് (pay off) വാക്ക് തന്നു. കൂടുതലായി (further payment) കുറച്ച് പണം കൂടി അദ്ദേഹം വാഗ്ദാനം ചെയ്തു, പക്ഷെ ഞാൻ അത് സ്വീകരിക്കാൻ വിസമ്മതിച്ചു (refused to accept).
(ചെറിയ മാറ്റങ്ങളോടെ)

Engine Trouble by Ruskin Bond About the Author

R. K. Narayan (1906 – 2001) is widely regarded as one of India’s finest English writers. Narayan’s simple, humorous writing style captures the beauty of life in a fictional Indian village-Malgudi, which serves as the setting for many of his stories. His notable works include The Guide (1958), which won the award of the Sahitya Akademi, India’s National Academy of Letters. It was later adapted into a popular film.

Among his other works are over 200 short stories, an autobiography My Days, a collection of essays My Dateless Diary and retellings of the Indian epics The Ramayana and The Mahabharata. Narayan has received several honours, including the Padma Vibhushan in 2000. He was nominated to the Rajya Sabha in 1986.

In parliament R. K. Narayan raised the issue of heavy schoolbags. His speech had an immediate impact. Governments across the country acted upon the suggestion, and in some cases the weight of the school bag dropped by 50%.

Here is an excerpt from Narayan’s speech in the Rajya Sabha.
I am taking this honorable House to another world. In the stress of concerns of the adult world, the problems, or rather, the plight of children are unnoticed. I am not referring to any particular class but to childhood itself. Schoolbags have become an inevitable burden for the child. I am now pleading for abolition of the school bag by an Ordinance, if necessary. I have investigated and found that an average child carries strapped to his back like a pack-mule, not less than 3 – 6 k.g. of books, notebooks and other paraphernalia of modern education, in addition to a lunch box and water bottles.

Parents often use SCERT Kerala Syllabus 8th Standard English Notes Pdf Unit 3 Chapter 1 Talking of Science Questions and Answers Activities Notes to assist their kids with homework.

Class 8 English Talking of Science Question Answer Activities

Talking of Science Questions and Answers Class 8

Class 8 English Unit 3 Question Answer

8th Standard English Talking of Science Question Answer

Question 1.
Do you think that asking questions is fundamental to all scientific exploration? How do questions move science forward?
ചോദ്യങ്ങൾ ചോദിക്കുന്നത് എല്ലാ ശാസ്ത്രീയ പര്യ വേക്ഷണങ്ങൾക്കും അടിസ്ഥാനമാണെന്ന് നിങ്ങൾ കരുതുന്നുണ്ടോ? ചോദ്യങ്ങൾ എങ്ങനെയാണ് ശാസ്ത്ര ത്തെ മുന്നോട്ട് നയിക്കുന്നത്?
Answer:
Yes, asking questions is fundamental to all scientific exploration. Questions move science forward because every scientific discovery begins with a question like “Why does this happen?” or “How does this work?”. These questions create a problem to be solved. Scientists then conduct experiments and do research to find the answer. Each new answer can lead to more questions, and this continuous cycle of questioning and seeking answers is what drives scientific progress.

Question 2.
‘Curiosity is at the heart of science.’ Do you agree?
ജിജ്ഞാസയാണ് ശാസ്ത്രത്തിന്റെ ഹൃദയം. നിങ്ങൾ യോജിക്കുന്നുണ്ടോ?)
Answer:
Yes, I completely agree with this statement. Curiosity is the deep desire to know or learn something new. As Dr. Ajith said in the interview, this curiosity is what “drives the quest for knowledge.” Without curiosity, a person would not ask questions or search for answers, and therefore, science would not exist.

Question 3.
How does observation help us understand natural phenomena?
പ്രകൃതി പ്രതിഭാസങ്ങളെ മനസ്സിലാക്കാൻ നിരീക്ഷണം നമ്മെ എങ്ങനെ സഹായിക്കുന്നു?
Answer:
Observation is the first and most important step in understanding natural phenomena. By carefully watching something-like the stars at night, a plant growing, or the weather changing-we can collect information and notice patterns. This helps us to ask meaningful questions and form an initial guess (a hypothesis). Scientists then test this guess through experiments, which also require careful observation.

Question 4.
What are the unsolved mysteries you would like to solve, with the help of science?
ശാസ്ത്രത്തിന്റെ സഹായത്തോടെ നിങ്ങൾ പരിഹരിക്കാ ൻ ആഗ്രഹിക്കുന്ന ഉത്തരം കിട്ടാത്ത രഹസ്യങ്ങൾ എന്തെ ല്ലാമാണ്?
Answer:
With the help of science, I would like to solve some of these mysteries:

• Is there life on other planets in our universe?
• Can we find a complete cure for diseases like cancer?
• How can we generate clean energy for everyone without harming the planet?
• Is time travel possible?

Question 5.
Do you want to become a scientist? How will you equip yourself for this?
നിങ്ങൾക്ക് ഒരു ശാസ്ത്രജ്ഞനാകാൻ ആഗ്രഹമുണ്ടോ? ഇതിനായി നിങ്ങൾ എങ്ങനെ സ്വയം സജ്ജരാകും?
Answer:
Yes, I want to become a scientist. To equip myself for this, I will:

• Study my science and mathematics subjects well in school.
• Always stay curious and ask a lot of questions about the world around me.
• Read many science books and articles to understand what is already known.
• Try to do small science projects and experiments.
• As Dr. Ajith advised, I will follow my interest with passion and work hard.

Talking of Science Class 8 Question Answer – Let’s Rewind

Question 1.
Books remain a source of reliable information unlike most of what we get online.” Do you agree? Give reasons.
ഓൺലൈനിൽ ലഭിക്കുന്ന മിക്ക വിവരങ്ങളെയും പോലെ യല്ലാതെ, പുസ്തകങ്ങൾ വിശ്വസനീയമായ വിവരങ്ങളു ടെ ഉറവിടമായി നിലനിൽക്കുന്നു. നിങ്ങൾ യോജിക്കു ന്നുണ്ടോ? കാരണങ്ങൾ നൽകുക.
Answer:
Yes, I agree with this statement. Books are generally more reliable because they are often written by experts and go through a process of editing and fact-checking before they are published. In contrast, a lot of information on the internet can be published by anyone without any verification, so it can sometimes be inaccurate, biased, or just a personal opinion rather than a fact.

Question 2.
How does asking questions help in developing our understanding?
ചോദ്യങ്ങൾ ചോദിക്കുന്നത് നമ്മുടെ ധാരണ വികസി പിക്കാൻ എങ്ങനെ സഹായിക്കുന്നു?
Answer:
Asking questions is the first step to learning. When we ask a question, we identify a gap in our knowledge. This pushes our minds to search for answers, which makes us read more, think critically, and connect different ideas. This active process of seeking answers helps us to develop a much deeper and clearer understanding of a topic.

Question 3.
Why does Dr. Ajith Parameswaran say that anyone can become a scientist?
എന്തുകൊണ്ടാണ് ഡോക്ടർ അജിത് പരമേശ്വരൻ ആർ ക്കും ഒരു ശാസ്ത്രജ്ഞനാകാം എന്ന് പറയുന്നത്?
Answer:
Dr. Ajith says that “anyone can become a scientist” because the most important quality needed is a child-like curiosity and a passion for knowledge. These are qualities that any person can have, regardless of their background. While becoming a world-famous scientist might be rare, anyone with curiosity and a willingness to work hard can learn, ask questions, and contribute to science.

Question 4.
What, in your opinion, are the essential qualities of a good scientist? Mention any two.
നിങ്ങളുടെ അഭിപ്രായത്തിൽ, ഒരു നല്ല ശാസ്ത്രജ്ഞന്റെ പ്രധാന ഗുണങ്ങൾ എന്തെല്ലാമാണ്? ഏതെങ്കിലും രണ്ട ണ്ണം പറയുക.
Answer:
In my opinion, two essential qualities of a good scientist are:

Deep Curiosity: A strong desire to always ask questions and understand why things are the way they are.

Honesty: The ability to look at evidence without bias, admit when they don’t know something, and accept the truth even if it is different from what they initially believed.

Question 5.
Do you now agree that science is entirely different from mere opinion? Why?
ശാസ്ത്രം കേവലം അഭിപ്രായത്തിൽ നിന്ന് തികച്ചും വ്യത്യ സ്തമാണെന്ന് നിങ്ങൾ ഇപ്പോൾ യോജിക്കുന്നുണ്ടോ? എന്തുകൊണ്ട്?
Answer:
Yes, I agree that science is entirely different from a mere opinion. An opinion is a personal belief that doesn’t need proof. Science, however, is a systematic method based on observation, experimentation, and evidence. A scientific conclusion is accepted only after it has been tested and verified, whereas an opinion is just what someone thinks or feels.

Talking of Science Activities

Class 8 English Talking of Science Activities Pdf – Let’s recall and recreate

Activity 1

A. Let’s now consider the features of a good interview.
• Rapport between interviewer and interviewee
• Conversational style
• ………………………………………………..
• ………………………………………………..
• ………………………………………………..
• ………………………………………………..

ഇനി, ഒരു നല്ല അഭിമുഖത്തിന്റെ സവിശേഷതകൾ പരി ഗണിക്കാം
Answer:

• Rapport between interviewer and interviewee
• Conversational style
• Well-researched questions
• Active listening by the interviewer
• Clear structure (Introduction, Body, Conclusion)
• Open-ended questions that encourage detailed answers

B. Now, prepare a few relevant questions for an interview with a prominent person in your locality.
Could you please tell us something about your early life?
• ………………………………………………..
• ………………………………………………..
• ………………………………………………..
• ………………………………………………..
• ………………………………………………..
ഇനി, നിങ്ങളുടെ പ്രദേശത്തെ ഒരു പ്രമുഖ വ്യക്തിയു മായുള്ള അഭിമുഖത്തിനായി ഏതാനും പ്രസക്തമായ ചോദ്യങ്ങൾ തയ്യാറാക്കുക
Answer:
For interviewing a social worker or an environmentalist

• Could you please tell us something about your early life?
• What motivated you to start your work in this field?
• Could you share one of the biggest challenges you have faced in your journey?
• What has been your most satisfying achievement so far?
• What is your message to the youth of our locality?

C. Conduct mock interviews in pairs.

Std 8 English Talking of Science Question Answer – Activity 2

Go though the following notice:

NOTICE
H.S.S Malgudi
Inauguratiion of the Library Building

(Dear students and parents)
The inauguratiion of the new library building is scheduled as detailed below.
Date : 20 December 2024
Timè : 10 a.m
Venue : Library Building, H.S.S Malgudi
The inaugural ceremony will be followed by a digital display of rare books. All students, teachers and parents are cordially invited to the function.
Malgudi
15 November 2024

(Seal)

[Signature]
[Name]
[Designation]

A. What is the purpose of a notice?
…………………………………………………………………..
…………………………………………………………………..

ഒരു നോട്ടീസിന്റെ ഉദ്ദേശ്യം എന്താണ്?
Answer:
The purpose of a notice is to formally communicate important information to a specific group of people or the public. It is used to announce events, meetings, competitions, or to give instructions and make announcements in a brief, clear, and direct way.
Here are some other kind of notices?

1. Lost and Found
2. Warning
3. Change of Name

B. What are the key features of a notice? Discuss.
• Objectivity
• ………………………………………………..
• ………………………………………………..
• ………………………………………………..
ഒരു നോട്ടീസിന്റെ പ്രധാന സവിശേഷതകൾ എന്തെല്ലാമാ ണ്? ചർച്ച ചെയ്യുക.
Answer:
The key features of a notice are:
Objectivity: It presents information as facts, without personal opinions.

• Clarity and Brevity: The language must be simple, clear, and short.
• Formal Tone: It should always be written in a formal style.
• Complete Information: It must include all necessary details like the event, date, time, venue, and who it is for (answering What, When, Where, Who).
• Proper Format: It follows a specific format including the name of the issuing authority, the word “NOTICE”, a heading, date, and the signature with designation of the person issuing it.

C. Here is the format of a programme notice. Complete it based on your understanding of a notice.

ഒരു പ്രോഗ്രാം നോട്ടീസിന്റെ ഘടന താഴെ നൽകുന്നു. നോട്ടീസിനെക്കുറിച്ചുള്ള നിങ്ങളുടെ ധാരണ വെച്ച് അത് പൂർത്തിയാക്കുക.
Answer:

NOTICE
Name of the Organisation
Headig/Title of the notice

(……………………)
(Body of the notice) This section contains all the details of the event, such as the purpose, date, time, venue, and who the notice is intended for.

Place
Date

Seal

[Signature]
[Name]
[Designation]

D. What do you expect to find in the body of a notice?
…………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………….
ഒരു നോട്ടീസിന്റെ പ്രധാന ഭാഗത്ത് (body) നിങ്ങൾ എന്തെല്ലാമാണ് പ്രതീക്ഷിക്കുന്നത്?
Answer:
In the body of a notice, you expect to find all the essential information about the event, clearly and concisely. This includes:

• The purpose or name of the event (e.g., a competition, a meeting, an inauguration).
• When: The date and time of the event.
• Where: The venue or location of the event.
• Who: The target audience for whom the notice is meant (e.g., all students, members of a club).
• Whom: The contact person for any queries (if applicable).
• Specific Instructions: Any other important details or instructions related to the event.

E. As the Secretary of the Science Club of your school, you plan to conduct a science exhibition. Prepare a notice giving details of the programme
Answer:

NOTICE
MODEL HIGH SCHOOL, KOZHIKODE
SCIENCE EXHIBITION 2025

This is to inform all students that the Science Club of our school is organising a Science Exhibition on Saturday, 5 July 2025, from 10:00 a.m. to 4:00 p.m. in the School Auditorium. The exhibition aims to foster a spirit of scientific inquiry and creativity among students.

Students from classes 8 to 10 who wish to exhibit their models or projects are requested to register their names with the undersigned on or before 28 June 2025. All students, teachers, and parents are cordially invited to visit the exhibition and encourage our young scientists.

Kozhikode
20 June 2025

[Signature]
[Arjun K]
[Secretary science Club]

Talking of Science Class 8 Question Answer – Activity 3

Human-animal conflicts and extreme weather events such as flash floods and landslides are on the increase today.
A. Try to list some of the probable causes of these events.
• Misuse of land
• …………………………………….
• …………………………………….
• …………………………………….
മനുഷ്യ – മൃഗ സംഘർഷങ്ങളും, മിന്നൽ പ്രളയങ്ങൾ, ഉരു ൾപൊട്ടലുകൾ പോലുള്ള അതിതീവ്രമായ കാലാവസ്ഥാ സംഭവങ്ങളും ഇന്ന് വർദ്ധിച്ചുവരികയാണ്.
ഇവയുടെ സാധ്യമായ ചില കാരണങ്ങൾ പട്ടികപ്പെടു ത്താൻ ശ്രമിക്കുക.
Answer:

• Misuse of land
• Deforestation: Cutting down forests destroys animal habitats, forcing them to enter human areas. It also loosens soil, causing landslides.
• Climate Change and Global Warming: Increased pollution is warming the planet, leading to more intense, unpredictable rains and floods.
• Improper Waste Management: Dumping garbage near forests attracts wild animals to human areas.
• Construction in Ecologically Sensitive Areas: Building houses and resorts in hilly areas and near rivers increases the risk of natural disasters

B. List some mysteries of Nature that remain unsolved. Write a short note on any one of these mysteries.
പ്രകൃതിയിലെ, ഉത്തരം കണ്ടെത്താനാവാത്ത ചില രഹ സ്യങ്ങൾ പട്ടികപ്പെടുത്തുക. അവയിലൊന്നിനെക്കുറിച്ച് ഒരു ചെറു കുറിപ്പ് എഴുതുക.
Answer:
Some Unsolved Mysteries of Nature:

• Are we alone in the universe? (Is there extraterrestrial life?)
• What is dark matter and dark energy?
• How exactly did life begin on Earth?
• How do some animals migrate thousands of kilometers so accurately?

Short note on: Are we alone in the universe?
The universe is incredibly vast, with billions of galaxies, each containing billions of stars. Many of these stars likely have planets orbiting them, just like Earth orbits the Sun. This makes scientists believe that it is highly probable that life exists on other planets too. However, despite searching for signals with powerful telescopes for many years, we have not yet found any definite proof of life outside Earth. This question-whether we are the only living beings in this enormous cosmos-remains one of the biggest and most exciting unsolved mysteries of science.

Talking of Science Class 8 Questions and Answers Pdf – Activity 4

Look at the collage below. What is this collage about? Discuss

This collage is about the history and progress of science and invention. It shows many important scientific discoveries and technological advancements that have changed human history, such as the light bulb, the steam engine, the airplane, atomic models, and also features famous scientists like Albert Einstein.

• Now, prepare a collage on recent disasters. Note your suggestions to prevent natural calamities in the space below.
……………………………………………………………………………………………..
………………………………………………………………………………………………
ഇനി, സമീപകാല ദുരന്തങ്ങളെക്കുറിച്ച് ഒരു കൊളാഷ് തയ്യാറാക്കുക. പ്രകൃതി ദുരന്തങ്ങൾ തടയുന്നതിനുള്ള നിങ്ങ ളുടെ നിർദ്ദേശങ്ങൾ താഴെ നൽകിയിട്ടുള്ള സ്ഥലത്ത് കുറിക്കുക.
Answer:
Suggestions to prevent natural calamities:
പ്രകൃതി ദുരന്തങ്ങൾ തടയാനുള്ള നിർദ്ദേശങ്ങൾ:
Plant More Trees (Afforestation): We must plant more trees because their roots hold the soil together, which helps prevent landslides. Forests also play a big role in controlling climate.

Stop Deforestation: We must stop cutting down forests, especially in hilly areas and on river banks.

Reduce Pollution: By using less plastic, saving electricity, and using public transport, we can help reduce global warming, which is a major cause of extreme weather.

Avoid Building in Sensitive Areas: We should avoid constructing large buildings in areas that are prone to floods and landslides.

Proper Waste Management: Never throw waste, especially plastic, into rivers, canals, and drainage systems, as this can block water flow and cause floods.

Talking of Science Notes – Activity 5

The story of science is the story of inventions and discoveries that changed the world.

Now, let’s attempt a ‘Just A Minute’ (JAM) speech about scientific inventions that changed the world, using the following indicators.
ശാസ്ത്രത്തിന്റെ കഥ, ലോകത്തെ മാറ്റിമറിച്ച കണ്ടുപിടുത്തങ്ങളുടെയും കണ്ടെത്തലുകളുടെയും കഥയാണ്. ഇനി, ലോക ത്തെ മാറ്റിമറിച്ച ശാസ്ത്രീയ കണ്ടുപിടുത്തങ്ങളെക്കുറിച്ച്, താഴെ നൽകിയിട്ടുള്ള സൂചകങ്ങൾ ഉപയോഗിച്ച് ഒരു ജസ്റ്റ് എ മിനിറ്റ് (JAM) പ്രസംഗം തയ്യാറാക്കാം.
• The name of the inventor(s)
• Impact of the invention/discovery
• Positive and negative effects.
Answer:
(JAM Speech on the Invention of the Wheel)

A very good morning to everyone. The invention I am going to talk about for the next minute is one of the most important in human history – the Wheel.

It’s hard to name a single inventor, as the wheel was likely invented around 3500 BC in Mesopotamia, but it wasn’t one person’s idea. The impact of the wheel was truly revolutionary. Initially used for making pottery, its most significant use came in transportation. Carts with wheels allowed people to transport heavy goods over long distances easily. This led to the growth of trade, agriculture, and the development of cities.

The positive effects are countless; from cars, trains, and airplanes to tiny gears in watches, our modern world runs on the principle of the wheel. However, one could argue that a negative effect is the pollution caused by the vehicles that depend on it.

In conclusion, the simple invention of the wheel set human civilization in motion, paving the way for almost every other mechanical invention that followed.

Thank you.

Class 8 English Talking of Science Activities Pdf – Activity 6

Cracking the Code: The Wonder of Science (കോഡ് കണ്ടെത്താം. ശാസ്ത്രത്തിന്റെ അണ്ടുതം)
We use a number of gadgets in our daily life. Pick any gadget of your choice and describe its features.
Here is a sample
Features of a Closed-circuit Television (CCTV) Camera
• high resolution pictures
• night vision
• wide view
• ………………………….
• Now, write the features of any of the following.
• GPS
• smart watch
• ………………………….
ഇനി, താഴെ നൽകിയിട്ടുള്ളവയിൽ ഏതെങ്കിലും ഒന്നി ന്റെ സവിശേഷതകൾ എഴുതുക
Answer:
Features of GPS (Global Positioning System):

• Provides real-time location tracking on a map.
• Gives turn-by-turn voice navigation to reach a destination.
• Estimates travel time and distance.
• Shows live traffic information and suggests faster routes.
• Helps in finding nearby places like restaurants, hospitals, or petrol pumps

Features of a Smartwatch:

• Displays time, date, and has customizable watch faces.
• Connects to a smartphone to show notifications for calls, messages, and apps.
• Tracks health and fitness activities like heart rate, step count, calories burned, and sleep patterns.
• Allows users to make and receive calls directly from the watch.
• Has built-in GPS for tracking out door activities like running and cycling.
• Can be used for contactless payments and controlling music.

8th Standard English Talking of Science Question Answer – Activity 7

A. We have learned that curiosity and observation are important parameters of the scientific method. Let’s now conduct a simple experiment and observe the results.
Answer:
Dancing Raisins Experiment
Materials required:
(a) Raisins
(b) A glass
(c) Soda or sparkling water
(d) Water

Instructions:
1. Half-fill the glass with soda.
2. Drop 5 – 7 raisins into the soda.
3. Observe
4. Slowly pour water into the glass.
5. Observe what happens.

B. Now, prepare a detailed procedure of your experiment. The first and last sentences are given. Use appropriate linkers.
First, half-fill the glass with soda. Add some raisins to the carbonated solution.
…………………………………………………………………………………………………………………………….. …………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………….
………………………………………………………………………………………………………….. Finally, observe the raisins for a few minutes.
ഇനി, നിങ്ങളുടെ പരീക്ഷണത്തിന്റെ വിശദമായ പ്രവർ നക്രമം തയ്യാറാക്കുക. ആദ്യത്തെയും അവസാന ത്തെയും വാക്യങ്ങൾ നൽകിയിട്ടുണ്ട്. അനുയോജ്യമായ യോജിപ്പിക്കാനുള്ള വാക്കുകൾ (linkers) ഉപയോഗിക്കുക.
Answer:
First, half-fill the glass with soda. Next, gently drop five to seven raisins into the soda and observe their movement for a minute. After that, slowly pour plain water into the glass until it is about three-quarters full. Then, watch carefully to see how the addition of water affects the raisins. Finally, observe the raisins for a few minutes.

C. Now, describe what happens to the raisins when you pour water into the glass Why does this happen? Write your explanation in 2 – 3 sentences.
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ഇനി, ഗ്ലാസിലേക്ക് വെള്ളം ഒഴിക്കുമ്പോൾ ഉണക്കമുന്തിരിക്ക് എന്ത് സംഭവിക്കുന്നു എന്ന് വിവരിക്കുക. എന്തുകൊണ്ടാണ് ഇത് സംഭവിക്കുന്നത്? നിങ്ങളുടെ വിശദീകരണം 2 – 3 വാക്യ ങ്ങളിൽ എഴുതുക.
Observation: When water is poured into the glass, the “dancing” movement of the raisins slows down, and eventually, they stop moving and sink to the bottom.

Explanation: This happens because the soda contains dissolved carbon dioxide gas. These tiny gas bubbles stick to the raisin’s surface, lifting it to the top. When we add plain water, it dilutes the soda, reducing the number of available gas bubbles. Without enough bubbles to lift them, the raisins can no longer float and therefore stop “dancing”.