MCQ
An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency ... $\%$
- A$5$
- ✓$20$
- C$0$
- D$0.5$
✓
Answer
Correct option: B.
$20$
b
(b) When observer moves towards stationary source then apparent frequency
(b) When observer moves towards stationary source then apparent frequency
$n' = \left[ {\frac{{v + {v_O}}}{v}} \right]\,n$
$ = \left[ {\frac{{v + v/5}}{v}} \right]\,n$$ = \frac{6}{5}n = 1.2n$
Increment in frequency $ = 0.2 n$
so percentage change in frequency = $\frac{{0.2n}}{n} \times 100= 20\%. $
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