Wave Motion 5 Question 10
10. The spread of frequency as observed by the passengers in train $B$ is
(2007, 4M)
(a) $310 Hz$
(b) $330 Hz$
(c) $350 Hz$
(d) $290 Hz$
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Answer:
Correct Answer: 10. (a)
Solution:
- For the passengers in train $B$, observer is receding with velocity $30 m / s$ and source is approaching with velocity $20 m / s$.
$\therefore \quad f _1^{\prime}=800\left(\frac{340-30}{340-20}\right)=775 Hz$
and
$$ f _2^{\prime}=1120\left(\frac{340-30}{340-20}\right)=1085 Hz $$
$\therefore$ Spread of frequency $=f _2^{\prime}-f _1^{\prime}$
$$ =310 Hz $$
