Question

Fill in the blank
A point source emits sound equally in all direction in a non-absorbing medium. Two point $P$ and $Q$ are at a distance of $9m$ and $25m$ respectively from the source. The ratio of the amplitudes of the waves at $P$ and $Q$ is..

Answer 1

$\text{Intensity}\propto \frac{1}{[\text{distance}{]}^2}$

$\Rightarrow \frac{I_P}{I_B}=(\frac{d_B}{d_P}{)}^2=\frac{625}{81}$

$\text{Intensity}\propto [\text{Amplitude}{]}^2$

$\therefore \frac{I_P}{I_Q}=\frac{A_P^2}{A_Q^2}$

$\therefore \frac{A_P}{A_Q}=\sqrt{\frac{625}{81}}=\frac{25}{9}$

$\therefore A_P:A_Q=25:9$