If the amplitude of a wave at a distance `r` from a point source is `A`, the amplitude at a distance `2 r` will be

Options

A. `2A`
B. `A`
C. `A/2`
D. `A/4`

Answer

C

Explanation

As we know that `lpropA^(2)`
Also `lprop 1/(r^(2))` (inverse square law)
`impliesA prop 1/r`
`:.A'=A/2`