Question

A body is vibrating 7200 times in one minute. If the velocity of sound is 360 m/s, find (i) frequency of the vibration in Hz, (ii) the wavelength of the sound produced.

• A. $120Hz,3m$
• B. $140Hz,3m$
• C. $120Hz,4m$
• D. $140Hz,4m$

Answer 1

The correct option is A $120Hz,3m$

(i) Frequency of vibration is defined as number of vibration per second ,

so , frequency , $f=$number of vibrations/time in second $=7200/60=120Hz$ ,

(ii) Now given , $v=360m/s$ and $f=120Hz$

by , $v=f\lambda$ ,

or $\lambda =v/f=360/120=3m$