Question

In the following statements, tick T against those which are true, and F against those which are false:
(a) Sound cannot travel in vacuum. (T/F)
(b) The number of oscillations per second of a vibrating object is called its time period. (T/F)
(c) If the amplitude of vibration is large, sound is feeble. (T/F)
(d) For human ears, the audible range is $20Hz$ to $20,000Hz$. (T/F)
(e) The lower the frequency of vibration, the higher is the pitch. (T/F)
(f) Unwanted or unpleasant sound is termed as music. (T/F)
(g) Noise pollution may cause partial hearing impairment. (T/F)

Answer 1

(a) True

Sound requires a material medium for travelling. It can travel in solid, liquid and gases. But it can't travel in the vacuum.

(b) False

The number of oscillations per second of a vibrating object is known as its frequency.

The time period is calculated for one oscillation. I.e it is the time taken by a vibrating object to complete one oscillation.

(c) False

The loudness of a sound is proportional to the square of the amplitude of its vibration.

When the amplitude of vibration of a sound is large, the sound is very loud. The sound is feeble for small amplitude.

(d) True

Humans cannot hear sounds of all frequencies. Humans can hear a sound whose frequency falls in the range of 20 Hz−20,000 Hz. The sound having frequency out of this range is inaudible to humans.

(e) False

The pitch of a sound is proportional to its frequency. As the frequency of vibration increases, the pitch of the sound also increases and vice-versa. A sound is said to be high pitched if its frequency of vibration is high, and is low pitched for a small frequency of vibration.

(f) False

Unwanted or unpleasant sounds are known as noise. Sounds that are melodious and pleasing to ear are known as music.

(g) True

Unwanted or unpleasant sounds are known as noise. If one is subjected to loud unpleasant sound continuously for a long time, then it may cause temporary hearing impairment.