Physics - Sound Wave Question with Solution | TestHub

Using the Doppler effect formula for a stationary observer and a source moving towards the observer:

$n^{\prime }=n\left(\frac{v}{v-v_s}\right)$

Given that the speed of the source is $v_s=\frac{v}{10}$:

$n^{\prime }=n\left(\frac{v}{v-\frac{v}{10}}\right)$

$n^{\prime }=n\left(\frac{v}{\frac{9v}{10}}\right)$

$n^{\prime }=n\left(\frac{10}{9}\right)$

The ratio of apparent to real frequency is:

$\frac{n^{\prime }}{n}=\frac{10}{9}$

Answer: $\frac{10}{9}$