A sound wave of frequency f propagating through the air with a velocity c , is reflected from a wall which is moving away from the stationary source with a constant speed v . The frequency of the reflected wave, measured by the observer at the position of the source is

Question

A sound wave of frequency f propagating through the air with a velocity c , is reflected from a wall which is moving away from the stationary source with a constant speed v . The frequency of the reflected wave, measured by the observer at the position of the source is (A) (f (. c - v .)/c + v) (B) (f (. c + v .)/c - v) (C) (f (. c + 2 v .)/c + v) (D) (f (. c - v .)/c - 2 v)

Tardigrade Admin · Accepted Answer

In first case observer (surface) is moving away. perceiver frequency

f^{^{'}} = f (\frac{c - v}{c})

In second case source (surface) is moving away. Perceived frequency

f^{^{''}} = f^{^{'}} (\frac{c}{c + v}) = f (\frac{c - v}{c + v})

Q. A sound wave of frequency $f$ propagating through the air with a velocity $c$ , is reflected from a wall which is moving away from the stationary source with a constant speed $v$ . The frequency of the reflected wave, measured by the observer at the position of the source is

$\frac{f ( c - v )}{c + v}$

$\frac{f ( c + v )}{c - v}$

$\frac{f ( c + 2 v )}{c + v}$

$\frac{f ( c - v )}{c - 2 v}$

In first case observer (surface) is moving away. perceiver frequency
$f^{^{'}} = f (\frac{c - v}{c})$
In second case source (surface) is moving away. Perceived frequency
$f^{^{''}} = f^{^{'}} (\frac{c}{c + v}) = f (\frac{c - v}{c + v})$

Q. A sound wave of frequency f propagating through the air with a velocity c , is reflected from a wall which is moving away from the stationary source with a constant speed v . The frequency of the reflected wave, measured by the observer at the position of the source is

c+vf(c−v)​

c−vf(c+v)​

c+vf(c+2v)​

c−2vf(c−v)​