As a spherical wavefront propagates, the amplitude (a) of a spherical wavefront varies with the distance r of the source

Options

A. inversely as `sqrtr` i.r., a `prop 1/sqrtr`
B. inversely as r i.r., a `prop ""1/r`
C. directly as r i.r., `a prop r`
D. directly as `sqrtr` i.e., `prop sqrtr`

Answer

B