Question

The source (S) of sound is moving constant velocity `v_(0)` as shown in diagram. An observer O listens to the sound emmited by the source. The observed frequency of the sound

A. continuously decreases
B. continuously increases
C. first decreases then increases
D. first increases then decreases.

Answer 1

Correct Answer - A
From figure, the velocity of approach `(V cos theta)` decreases as the source comes closer (as `theta` increases). And the velocity of separation also increases as `phi` will decreases. Hence the frequency of should as heard by the observed decreases continuously.