Introduction to Sound

Q. Which of the following is a mechanical wave?

1. Light
2. X-rays
3. Sound
4. Radio waves

Q. Sound of the explosion taking on other planets are not heard by a person on the earth. Why? [2 Mark]

Q. Distance between two compressions in a sound wave gives a measure of:

1. Wavelength
2. Time period
3. Amplitude
4. Phase

Q.

_____________is a type of energy induced vibrations.

Q.

Why do explosions on other planets not heard on the earth?

Q.

Describe in brief, with the aid of a labelled diagram, an experiment to demonstrate that a material medium is necessary for the propagation of sound.

Q. Some words describe actions. Many of them end in -ly.
The girl danced beautifully.
Fill in the blanks by changing the word in the brackets suitably.
(i) The girl slept _______ (sound)
(ii) The children finished their work _______ [quick]
(iii) The old man shouted _______ [loud]
(iv) The boys played _______ [quiet]
(v) Do your work _______ [neat]
(vi) I can do the sum _______ (easy)

Q. When sound waves travel from a rarer medium to a denser medium, its speed:

1. decreases
2. remain constant
3. increases
4. may increase or decrease

Q. Which of the following is/are properties of a sound wave?

1. It does not requires a medium to propagate.
2. It is a longitudinal wave.
3. It is a mechanical wave.
4. Travels faster than light.

Q.

Sound wave has different speeds in different mediums because:

1. more elastic the medium is, slower the speed.

2. more elastic the medium is, faster the speed.

3. lesser the volume, faster the speed.

4. less the density, slower the speed.

Q. Statement 1: No sound can be heard on the surface of the Moon.

Statement 2: High surface temperature of the Moon restricts sound propagation.

1. Only statement 1 is correct.
2. Only statement 2 is correct​.
3. Both the statements are correct.
4. Both the statements are incorrect.

Q. A big explosion on the Moon cannot be heard on the Earth. Which of the following statement is the correct explanation for this?

1. The explosion produces high frequency sound waves which are inaudible.
2. Moon has no atmosphere.
3. Sound waves are absorbed in the moon’s atmosphere.
4. Sound waves are absorbed in the earth’s atmosphere.

Q. Sound and light waves, both ______.

1. have the same speed
2. travel through vacuum
3. obey the laws of reflection
4. are forms of energy