NCERT Questions

Class 8
Chapter 13 Class 8 - Sound

## 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 20 Hz to 20,000 Hz. (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)

(a)   True

Sound needs a medium to travel. Since vacuum does not have a medium, sound cannot travel through vacuum.

(b) False

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

Time period is the time taken by the wave to one complete oscillation

(c) False

Loudness of sound is proportional to the amplitude.

If the amplitude is large, sound would be loud

If the amplitude is small, sound produced is feeble

(d) True

Human ears can hear a sound whose frequency range is between 20 Hz and 20,000 Hz.

(e) False

Pitch of sound is proportional to the frequency.

If frequency is low, sound would be of low pitch.

(f) False

Unwanted or unpleasant sound is termed as noise.

Sounds which is pleasant to hear is called Music

(g) True

Presence of Excessive sounds or Unwanted Sounds in our environment is called Noise Pollution

If a person hears the unwanted sound for a long time it may lead to partial hearing impairment

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