The source of sound generating a frequency of 3 kHz reaches an observer with a speed of 0.5 times the velocity of sound in air. The frequency heard by the observer is

Question

The source of sound generating a frequency of 3 kHz reaches an observer with a speed of 0.5 times the velocity of sound in air. The frequency heard by the observer is (A) 1 kHz (B) 2 kHz (C) 4 kHz (D) 6 kHz

Tardigrade Admin · Accepted Answer

Apparent frequency heard will be n '= n (n/v-vs) v = velocity of sound, vs= velocity of source of sound n = frequency -3 KHz ∴ n'=3 × (v/v-0.5v) =3 × (v/0.5v)=6 k H z

Q. The source of sound generating a frequency of $3 k Hz$ reaches an observer with a speed of $0.5$ times the velocity of sound in air. The frequency heard by the observer is

1 kHz

2 kHz

4 kHz

6 kHz

Apparent frequency heard will be $n^{'} = n \frac{n}{v - v _{s}}$
$v$ = velocity of sound,
$v_{s} =$ velocity of source of sound
$n =$ frequency $- 3 KHz$
$∴ n^{'} = 3 \times \frac{v}{v - 0. 5 _{v}}$
$= 3 \times \frac{v}{0. 5 _{v}} = 6 k Hz$

Q. The source of sound generating a frequency of 3kHz reaches an observer with a speed of 0.5 times the velocity of sound in air. The frequency heard by the observer is