The comprehensive approach in Kerala Syllabus 9th Standard Physics Notes Pdf Chapter 8 Sound Notes Extra Questions and Answers ensures conceptual clarity.
Kerala Syllabus Std 9 Physics Chapter 8 Sound Extra Questions and Answers
Question 1.
Write the vibrating part in the following sources of sound
a) Flute
b) violin
c) Chenda
Answer:
a) Flute – Air columns
b) Violin – String & wooden frame
c) Chenda – Diaphragm
Question 2.
State true or false
i) The linear motion of objects produces sound.
ii) A rubber, when plucked is in vibration
iii) The main vibrating part of an Ilathalam is the Strings.
Answer:
i) False
ii) True
iii) False
Question 3.
Give two examples of wind instruments.
Answer:
Mouth organ, Saxophone
Question 4.
Give two examples of instruments that produce sound due to the vibration of a stretched membrane.
Answer:
Drum, Mizhavu
Question 5.
How does the human body make sound?
Answer:
Sound is produced when the vocal cords in the upper part of the larynx vibrate.
Question 6.
Match the following
| Cicada | Vocal cords |
| Bugle | The wings |
| Humans | Stretched membrane |
| Mridangam | Air column |
Answer:
| Cicada | The wings |
| Bugle | Air column |
| Humans | Vocal cords |
| Mridangam | Stretched membrane |
Question 7.
Classify the following musical instruments based on their main vibrating part (Flute, Guitar, Tabla, Veena, Drums, Clarinet)
Answer:
Flute, Clarinet – Air column
Guitar,Veena – Strings
Tabla, Drums – Stretched membrane
Question 8.
Write any three uses of sound.
Answer:
- For communication
- Sounds of ambulance and fire engine sirens to avoid traffic on road
- Alarm and siren sounds to indicate time
Question 9.
In which medium sound has maximum speed, why?
Answer:
Sound has maximum speed in solid. Because molecules in solid medium are closely packed. This allows sound waves to travel more quickly through it.
Question 10.
We can hear the sound when we are speaking through a speaking tube made by using a paper cup and thread.
a) In which medium sound travels?
b) What change will occur If we use an aluminium rod instead of the string?
c) Can the sound be heard if we speak in the moon by using the speaking tube?
Answer:
a) Thread
b) Speed of sound increases
c) No
Question 11.
Among the given media the speed of sound is fastest In .
(Helium, aluminium, air, sea water)
Answer:
Aluminium
Question 12.
Which are the factors that affect the speed of sound?
Answer:
Temperature, density of the medium.
Question 13.
Appu and ammu on their vacation visited a snake park. Their conversion is given below.
Appu : Snakes can hear all the sounds around it.
Ammu: Snakes cannot hear sounds, but they utilise the vibration due to sounds for their needs.
Who Is right. Justify.
Answer:
Ammu is right. Snakes utilise sound transmission through the floor for catching prey and self-defence.
Question 14.
Can sound travel through water? If so, how It is utilised by aquatic animals?
Answer:
Yes, sound can travel through water. Aquatic animals such as dolphins and whales communicate by sound transmission through seawater.
Question 15.
Students In a school made a toy telephone using a matchbox and thread.
a) Can they communicate with each other using the toy telephone?Explain
b) Can this be used for communication in outer space?
c) If not what device is to be used for communication ¡n space?
Answer:
a) Yes. They can communicate with each other using a toy telephone. Sound travels through solids. Here, sound travels through the matchbox and the thread and reaches the ears.
b) No. A medium is necessary for sound to travel. There is no medium in space.
c) Radio devices should be used.
Question 16.
Tabulate the given statements as those related to sound and light.
i) Travels through vacuum
ii) Cannot travel through the vacuum
iii) Speed In air is 350m/s
iv) Speed in air is 3 × 108 m/s
Answer:
| Sound | Light |
| ii) Cannot travel through vacuum | i) Travels through vacuum |
| iii) Speed in air is 350m/s | iv) Speed in air is 3 × 108 m/s |
Question 17.
Raju conducted an experiment using an electric bell. First, he listened to the sound of the bell Then he placed the bell in a jar and sucked out the maximum amount of the air in it using a tube.
a) In both cases, is there a difference in the sound heard?
b) What is the difference in sound heard?
c) What happens if the whole air is sucked out?
d) What is the inference he arrived at from the experiment?
Answer:
a)Yes
b) The sound keeps on diminishing in the second case more than in the first case because the amount of air is less when the bell is placed in ajar and the air in it is sucked.
c) No sound is heard
d) A medium is necessary for sound to travel.
Question 18.
Ben and Ken, while swimming in a pool, dived into its depths. They spoke to each other when they were underwater.
a) Can they hear each other?
b) Which ¡s the medium through which sound travels here?
Answer:
a) Yes
b) Water
Question 19.
State whether the given statements are true or false and correct the wrong statements.
i) Sound can travel only through solids
ii) Sound can travel through the vacuum
iii) Speed of sound is greater in solids
iv) Snakes use sound transmission through the floor for self-defence.
Answer:
i) False
Corrected statement- Sound can travel through solids,liquids and gases
ii) False
Corrected statement-Sound cannot travel through vacuum
iii) True
iv) True
Question 20.
Correct and redraw the flowchart indicating passage of sound through ear
Question 21.
Ear is the sense organ that helps us to hear But is it the only component required to sense sound. Explain.
Answer:
It is not the only component required to sense sound. There are three essential components to sense sound. They are source of sound,medium and the sense organ for hearing.
Question 22.
Name the parts labelled as C and R in the figure.
Answer:
C – High pressure region
R – Low pressure region
Question 23.
Sense of hearing is a gift. But there are many people around us who face challenges in hearing. What should be the approach to the hearing impaired?
Answer:
- Be empathetic
- Give consideration and include them in all activities
- Respect their needs
- Encourage participation in all activities
Question 24.
Ear health is also important for a healthy life.What are the steps to be followed for the protection of ear?
Answer:
- Do not put pointed objects in the ear
- Maintain hygiene
- Maintain Healthy lifestyle
- Stay away from extreme loud noises and while using headphones stick to a volume range that is said to be safe.
Question 25.
Tabulate the following as music and noise.
(Sound from a violin, Horn of a car, Crackers, Sound of cuckoo, Musical concerts, Sound of cicada)
Answer:
| Music | Noise |
| Sound from a violin | Crackers |
| Musical concerts | Sound of cicada |
| Sound of cuckoo | Horn of a car |
Question 26.
How do human beings contribute to noise pollution?
Answer:
Sound of vehicles, sound of air horn, sound of loudspeaker, horn, etc.
Question 27.
List the demerits and remedies of noise pollution.
Answer:
Demerits of noise pollution
It affects physical and mental health. They cause learning disability, deafness, high blood pressure, etc.
Remedies
- Make effective rules and regulations
- Avoid air horns
- Maintain the vehicles properly
- Use box-type loudspeaker
- Do not make sounds above 50 dB on the premises of courts, hospitals and educational institutions.
- Planting trees as much as possible.