In the figure shown below, a source of sound having power `12xx10^-6W` is kept at `O`, which is emitting sound waves in the directions as shown. Two surfaces are labelled as 1 and 2 having areas `A_1=2xx10^3m^2` and `A_2=4xx10^3m^2`, respectively
Q. find the intensity at both the surfaces.

Options

A. `I_1=12xx10^-6(W)/(m^2)`,`I_2=12xx10^-6(W)/(m^2)`
B. `I_1=6xx10^-9(W)/(m^2)`,`I_2=12xx10^-9(W)/(m^2)`
C. `I_1=6xx10^-9(W)/(m^2)`,`I_2=3xx10^-9(W)/(m^2)`
D. `I_1=12xx10^-9(W)/(m^2)`,`I_2=3xx10^-9(W)/(m^2)`

Answer

C

Explanation

`I=(P)/(A)`
so, `I_1=(P)/(A_1)` and `I_1=I_2=(P)/(A_1)`