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A straight line source of sound of lengt...

A straight line source of sound of length `L=10m`, emits a pulse of sound energy (in mW) is intercepted by an acoustic cylindrical detector of surface area `2.4cm^2`. Located at a perpendicular distance 7 m from the source ? The waves reach perpenduculary at the surface of the detector. The total emiited by the source in the form of sound is `2.2xx10^(4)W`. (use `pi=22//7`)

A

`12`

B

`9`

C

`25`

D

`16`

Text Solution

Verified by Experts

The correct Answer is:
A

Imagine a cylinder of radius 7 m and length 10 m. Intensity of sound at the surface of cylinder is same everywhere.
Therefore. `I=(P)/(2pirL)`
(As sound is propagating radially out only, sound energy doen not flow out through the end).
`I=50 W//m^(2)`
Energy intercepted by the detector `=IxxA=12mW`
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