Physics - Sound Wave Question with Solution | TestHub

The car acts as a source moving towards the stationary wall. The frequency of sound received by the wall is given by the Doppler effect formula:

$n^{\prime }=n\left(\frac{V}{V-V_1}\right)$

The wall reflects this sound, acting as a stationary source of frequency $n^{\prime }$. The driver acts as an observer moving towards this stationary source with velocity $V_1$. The frequency heard by the driver is:

$n^{\prime \prime }=n^{\prime }\left(\frac{V+V_1}{V}\right)$

Substituting the value of $n^{\prime }$ into the second equation:

$n^{\prime \prime }=n\left(\frac{V}{V-V_1}\right)\left(\frac{V+V_1}{V}\right)$

$n^{\prime \prime }=n\left(\frac{V+V_1}{V-V_1}\right)$

Answer: $\left(\frac{V+V_1}{V-V_1}\right)n$