Mark the following statements true or false. Rewrite the false statements correctly.
(a) Sound has three properties-loudness, frequency and quality.
(b) A sound with large amplitude is louder than one with small amplitude.
(c) The loudness of sound is measured in hertz.
(d) Shortening the string of a guitar lowers its pitch.
(e) The eardrum vibrates when sound waves enter the ear.
(f) Frequency is the number of vibrations per second.
(g) Echoes are produced by the absorption of sound.
(h) Sound travels fastest in solids.
(i) The quality of sound produced by all stringed instruments will be the same.
(j) Radha tightens the string of her veena to raise the pitch of sound.

State whether the following statements are true or false:

(a) Sound cannot travel in vacuum.

(b) The number of oscillations per second of a vibrating object is called its time-period.

(c) If the amplitude of vibrations is large, sound is feeble.

(d) The lower the frequency of vibration, the higher is the pitch.

(e) If the amplitude of vibrations is doubled, the loudness of sound also gets doubled.

(f) When the amplitude of vibrations is halved, the loudness of sound becomes one-fourth.

(g) Unwanted or unpleasant sound is termed as music.

(h) Noise pollution may cause partial hearing impairment.

Write true or false for each statement:

(a) When sound propagates in air,it does not carry energy with it.

(b) In a longitudinal wave,compression and rarefaction are formed.

(c) The distance from one compression to nearest rarefaction is called wavelength.

(d) The frequency is measured in second.

(e) The quality of sound depends on the amplitude of wave..

(f) The pitch of sound depends on frequency..

(g) Decibel is the unit of pitch of a sound.

Fill in the following blanks with suitable words :

(a) An echo is simply a ___ sound .

(b) Pitch of sound depends on ___ .

(c) Loudness of sound depends on ___ .

(d) Quality of sound depends on ___ .

(e) Echoes are caused by the ___ of sound .

Consider the following sound waves marked A, B, C and D :

(a) Which two waves represent sounds of the same loudness but different pitch ?

(b) Which two waves represent sounds of the same frequency but different loudness ?

(c) State whether all these sound waves have been produced by the same vibrating body or different vibrating bodies ?

(d) Which vibrating body/ bodies could have generated the sound waves shown here ?