In the following statements, tick 'T' against those which are true and 'F' against those which are false.

(a) Sound cannot travel in a 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 the vibration is large, the 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)

The sound from a mosquito is produced when it vibrates its wings at an average rate of 500 vibrations per second. What is the time period of the vibration?

Fill in the blanks with suitable words.

(a) Time taken by an object to complete one oscillation is called ……………

(b) Loudness is determined by the …………… of vibration.

(c) The unit of frequency is ……………

(d) Unwanted sound is called ……………

(e) Shrillness of a sound is determined by the …………… of vibration.

Identify the part which vibrates to produce sound in the following instruments.

(a) Dholak

(b) Sitar

(c) Flute