Question

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

• A. Have constant phase difference
• B. Be narrow
• C. Be close to each other
• D. Of same amplitude

Answer 1

The correct option is A Have constant phase difference

To obtain a well defined interference patterns, the intensity at points corresponding to destructive interference must be zero, while intensity at the point corresponding to constructive interference must be maximum. To accomplish this the necessary condition is that the two interference sources must be coherent, that is, they must keep a constant phase difference.