Extra Questions for Class 9 Science Chapter 12 Sound

Extra Questions for Class 9 Science Chapter 12 Sound

Very Short Answer Type

1. What is sound?
2. What is vibration?
3. Name the sound producing organ in humans.
4. Do the frequency of sound produced by men and women are same?
5. What types of medium is required for sound to travel?
6. Write the name of the organ through which human receives the sound.
7. What is the unit of frequency?
8. What is the name of the sound produced by irregular vibrations?
9. On which factor pitch of the sound depends?
10. What is the range of frequency that a human can hear?
11. What is the ultrasonic sound?
12. What is the unit of loudness?
13. What are sounds of frequencies below 20 Hz called?
14. In which medium the speed of the sound is maximum?
15. Can sound travel through vacuum?

Show Answer

1. Sound is a form of energy or the medium by which we can communicate with each other.
2. The to and fro motion of an object is called vibration.
3. Voice box or larynx
4. No, the frequency of sound of men and women are not same.
5. Sound can travel through solids, liquids and gases.
6. Ear
7. Hertz
8. Noise
9. The pitch of the sound depends on frequency.
10. Human can hear the sound of frequencies 20 Hz to 20,000 Hz
11. Sound having frequency above 20,000 Hz is called ultrasonic sound.
12. Decibel (dB)
13. Infrasonic sounds.
14. In solids, the speed of sound is maximum.
15. No, sound can not travel through vacuum.

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Short Answer Type

1. What do you understand by “audible” and “inaudible” range of sound?
2. Why do women have shriller voice than men?
3. How is sound produced?
4. Explain the importance of sound in our daily life.
5. Explain with the help of an activity that vibrating bodies produce sound.
6. Name the organ in human that produces sound. How does it work?
7. A pendulum oscillates with the frequency of 50 Hz. Find its time period?
8. How does loudness of the sound depends upon amplitude?
9. What do you understand by shriller sound?
10. What is the difference between noise and music?

Show Answer

1. Human ear can hear sound of frequency 20 Hz to 20000 Hz. Out of this frequency range, humans cannot hear it. So the sound having the frequency range 20 to 20000 Hz is called audible sound and out of this range is called inaudible sound.
2. Women have shorter vocal cords than men so the frequency of sound of women is greater than men. So women have shriller voice than men.
3. The vibrating bodies produce the sound. When a body vibrates, sound is produced. If vibrations are stopped the sound is not produced any more.
4. Sound play an important role in our daily life. Our life depends on sound for each and every action. Without sound we cannot know what others communicate or want to say. Sound enables us to communicate with each other.
5. Take a rubber band, put it around the longer side of a pencil box. Insert two pencils between the box and stretched rubber. Pluck the rubber band somewhere in the middle. You hear a sound and also see that rubber band vibrate. This activity shows that vibrating bodies produce sound.
6. In humans, the sound is produced by the voice box or larynx. The voice box has two vocal cords stretched across it, in such a way that it leaves a slit for the passage of air. When the lungs forces air through slit, the vocal cords vibrate to produce sound.
7. Time period = 0.02 s
8. Loudness of sound is directly proportional to the square of amplitude of vibration. It means that the loudness of sound increases with increase in its amplitude.
9. Sound of higher pitch is known as shriller sound. The pitch of the sound depends upon frequency of sound. The sound which have higher frequency of vibrations, have higher pitch.
10. The sound, which is unpleasant to ears is termed as noise. Noise is produced by irregular vibration. The sound which is pleasing to ears is known as music. Music is produced by regular vibrations.

Long Answer Type

1. With the help of an activity show that sound
   (i) can travel through solids
   (ii) cannot travel through vacuum.
2. What are the major sources of noise pollution ?
   What are the harmful effect of noise pollution?
3. Write the methods to control noise pollution.
4. Write the applications of the ultrasound.
5. How does loudness of sound is affected by amplitude?