A) 2
B) 4
C) 8
D) 10
Correct Answer: D
Solution :
Given: Frequency of sound produced by siren, f = 800 Hz Speed of observer, \[u=2m/s\] Velocity of sound, \[v=320\text{ }m/s\] No. of beats heard per second = ? No. of extra waves received by the observer per second \[=\pm 4\lambda \] \[\therefore \]No. of beats/ sec\[=\frac{2\times 2}{\frac{320}{800}}\left( \because \lambda =\frac{V}{f} \right)\] \[=\frac{2\times 2\times 800}{320}=10\]You need to login to perform this action.
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