Q.

A point source is emitting sound waves of intensity 16×10-8Wm-2 at the origin. The difference in intensity (magnitude only) at two points located at distances of 2 m and 4 m from the origin respectively will be ____ ×10-8Wm-2.            [2024]


Ans.

(3)

We know for point source, I1r2=K4πr2

r1=2m,  r2=4m=2r1

I0=16×10-8 W/m2

at 2m, I1=I0(2)2=16×10-84

I1=4×10-8

 At 4m, I2=I042=16×10-816=10-8

|I2-I1|=3×10-8 W/m2,  x=3