A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

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)

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.

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?

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

(a) Dholak (b) Sitar (c) Flute