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

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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.