Question

A source of sound is moving away from a stationary observer with a speed equal to the speed of sound. The apparent frequency heard by the observer will be:

• A. $n^3$
• B. $2n$
• C. $\frac{n}{2}$
• D. unchanged

Answer 1

The correct option is C $\frac{n}{2}$

$v_s=v=v^{\prime }$(say)

$v_0=0$

$\therefore f=f_0\frac{v^{\prime }}{2v^{\prime }}=\frac{f}{2}=\frac{n}{2}$