As a wave propagates,

Options

A. (a) the wave intensity remains constant for a sine wave
B. (b) the wave intensity decreases as the inverse of the distance from the source for a spherical wave
C. (c ) the wave intensity decreases as the inverse square of the distance from the source for a spherical wave
D. (d) total intensity of the spherical wave over the spherical surface centered at the source remains constant at all times.

Answer

A, C, D

Explanation

(a,c,d) For a plane wave, intensity (energy crossing per unit area per unit time) is constant at all points. But for a spherical wave, intensity at a distance `r` from a point source of power `(P)`, is given by `I = (P)/(4pir^(2))`
rArr `I prop (1)/(r^(2))`
But the total intensity of the spherical wave over the spherical surface centered at the source remains constant at all times.