For the sustained interference of light, the necessary condition is that the two sources should

Options

A. have constant phase difference
B. be narrow
C. be close to each other
D. of same amplitude

Answer

A

Explanation

The sources which produce sustained, i.e., observable interference are called coherent sources, in case of interference as `(I=I_(1)+I_(2)+2sqrt(I_(1)I_(2))cosphi)` interference will be sustained if the phase difference `phi` at a given point does not vary with time so phase difference between two sources must be constant.