A small source of sound moves on a circle as shown in the figure and an observer is standing at $O$. Let…
A small source of sound moves on a circle as shown in the figure and an observer is standing at $O$. Let $n_1$, $n_2$ and $n_3$ be the frequencies heard when the source is at $A$, $B$ and $C$ respectively. Then
$n_1 > n_2 > n_3$
$n_2 > n_3 > n_1$
$n_1 = n_2 > n_3$
$n_2 > n_1 > n_3$
Solution
At point $A$, source is moving away from observer, so apparent frequency $n_1 < n$ (actual frequency). At point $B$, source is coming towards observer, so apparent frequency $n_2 > n$ and point $C$, source is moving perpendicular to observer, so $n_3 = n$.
Hence, $n_2 > n_3 > n_1$
