Question

A source moves towards a stationary observer with a speed of 10m/s. If the frequency of the source is 10Hz what will be the wavelength of sound heard by the observer? Speed of sound = 330m/s.

(a) 32m

(b) 34m

(c) 33m

(d) 31m

The question was asked during an online interview.

My question is taken from Waves topic in section Waves of Physics – Class 11

Answer 1

Correct answer is (a) 32m

For explanation: Apparent frequency F = f(330+v0)/(330+v8)

= 10(330)/(330-10) = 10.31Hz.

Wavelength = 330/F

= 330/10.31

= 32.007m = 32m.