Question

A source of sound moves towards a listener with a velocity equal to that of sound. If the source emits n waves per second, then the listener moving away from the source with the same velocity receives

• A. n waves per sec
• B. 2n waves per sec
• C. zero waves per sec
• D. $\frac{n}{2}$

Answer 1

Answer: (C)

zero waves per sec

Given :

${\vartheta }_s=Vm/s$
${\vartheta }_0=Vm/s$
$\vartheta =Vm/s$
$\delta =nHz$

By doppler effect formula:
${\delta }^1=\delta \left(\frac{V-V_0}{V-V_s}\right)$

$=n\left(\frac{V-V}{V-V}\right)$

$=0$

So, zero waves per second are received by learner.