Two waves of the same frequency and amplitude super impose to produce a resultant disturbance of the same amplitude. The phase difference between the waves is.

Options

A. zero
B. `pi//3`
C. `pi//4`
D. `2pi//3`

Answer

D

Explanation

Let the amplitude of each wave be A and phase difference between them be `phi` . Then , `A = sqrt(A^(2) + A^(2) + 2 A^(2) cos phi) implies cos phi = - (1)/(2)` or `phi = (2pi)/(3)`