A straight line source of sound of length L = l0 m, emits a pulse of sound that travels radially outward from the source. What sound energy (in mW) is intercepted by an acoustic cylindrical detector of surface area 2.4 ${\mathrm{cm}}^2$, located at a perpendicular distance 7 m from the source? The waves reach perpendicularly at the surface of the detector. The total power emitted by the source in the forrn of sound is $2.2\times {10}^4 \mathrm{W}.(\mathrm{Use} \mathrm{\pi } = \frac{22}{7})$

• A

  12

• B

  9

• C

  25

• D

  16