As the wave propagates, choose the incorrect statement.

Options

A. the wave intensity remains constant for a plane curve
B. the wave intensity decreases as the inverse of the distance from the source for a spherical wave
C. the wave intesity decreases as the inverse square of the distance from the source for a spherical wave
D. the wave intensity decreases as the inverses of the distance for a line source.

Answer

B

Explanation

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 (energy transmitted per unit time) is given by
`I=(P)/(4pir^2)` or `Iprop(1)/(r^2)`
for a line source `I=(P)/(2pirl)` or `Iprop(1)/(r )`