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A point source emits sound equally in all directions in a non-absorbing medium. Two point `P` and `Q` are at distance of `2 m` and `3 m` respectively from the source. The ratio of the intensities of the wave at `P` and `Q` is :

A

`9 : 4`

B

`2:3`

C

`3:2`

D

`4:9`

Text Solution

Verified by Experts

The correct Answer is:
A
`I=(P)/(4pir^(2))`, `I prop (1)/(r^(2))` or `(I_(1))/(I_(2))=((r_(2))/(r_(1)))^(2)`
`:. (I_(1))/(I_(2))=((3)/(2))^(2)=(9)/(4)`
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