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A siren emitting sound of frequency 800...

A siren emitting sound of frequency `800 Hz ` is going away from a static listener with a speed of 30 m/s. Frequency of the sound to be heard by the listener is ( Take velocity of sound as 300 m/s )

A

727.3 Hz

B

481.2 Hz

C

644.8 Hz

D

286.5 Hz

Text Solution

Verified by Experts

The correct Answer is:
A
Here, `upsilon = 800 Hz, v_(s)=30 m//s, v = 300 m//s`. As the source is going away from the stationary observer, therefore.
`upsilon'=(v xx upsilon)/(v+v_(s))=(300xx800)/(300+30)=(300xx800)/(330)=727.3 Hz`.
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