If 20 waves are produced per second, what is the frequency in hertz?

Calculate the frequency of a wave whose time-period is 0.02 s.

What will be the change in the wavelength of a sound wave in air if its frequency is doubled?

Fill in the following blanks with suitable words

(a) Sound is caused by ………….

(b) A sound wave consists of places of higher pressure called ….. and places of …….. pressure called …………

(c) Wave speed in metres per second equals frequency in …………. Multiplied by ……….. in ………

(d) Sound cannot travel through ……….

(e) The speed of sound in a solid is ………… than the speed of sound in air.

(f) When the frequency of the sound is increased, the wavelength …………

What is vaccum? Explain why, sound cannot travel through vacuum?