The intensity of sound from a point source is 1.0 × 10−6m−2 at a distance of 5.0 m from the source. What will be the intensity at a distance of 25 m from the source?
The power of the sound wave is intensity × surface area
power =1 × 108 × 4π × 25
=100π 10−8 = 10−6π W
Intensity at 25m =powersurfacearea
=10−6π4π(25)2
=10−6625 × 4
=10−62500
=0.04 × 10−8 Wm−2