A source and an observer approach each other with same velocity 5… - Vidyadip

MCQ

A source and an observer approach each other with same velocity $50 \mathrm{~m} / \mathrm{s}$. If the apparent frequency is $435 \mathrm{sec}$, then the real frequency is

✓
$320 \mathrm{~sec}$
B
$360 \mathrm{~sec}$
C
$390 \mathrm{~sec}$
D
$420 \mathrm{~sec}$

✓

Answer

Correct option: A.

$320 \mathrm{~sec}$

$n^{\prime}=n\left[\frac{v+v_O}{v-v_S}\right] ;$ Here $v=332 \mathrm{~m} / \mathrm{s}$ and $v_0=v_s=50 \mathrm{~m} / \mathrm{s}$
$\Rightarrow 435=n\left[\frac{332+50}{332-50}\right] \Rightarrow n=321.12 \mathrm{sec}^{-1} \approx 320 \mathrm{sec}^1$

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