Question

A source of sound emitting a tone of frequency 200 Hz moves towards an observer with a velocity v equal to the velocity of sound. If the observer also moves away from then source with the same velocity v, the apparent frequency heard by the observer is

• A. 0 Hz
• B. 100 Hz
• C. 150 Hz
• D. 200 Hz

Answer 1

The correct option is D 200 Hz

As source and observer both are moving in the same direction with the same velocity, their relative velocity is zero.

So there is no Doppler effect and thus apparent frequency heard by the observer is same as that of the original frequency.

$\therefore$ $n^{\prime }=n=200Hz$