What is interference of light? Write two essential condition for sustained interference pattern to be produced on the screen.

Explanation

Conditions for sustained interference of light:
(i) The two sources should emit the light waves continuously.
(ii) The light waves should be of same wavelength.
(iii) The two light waves from the two sources should be of same amplitude for good constrast between dark and bright fringes.
(iv) The light waves from the two sources should either be in phase or have a constant phase difference.
(v) The two light sources of light must be close to each other,
(vi) The light sources should be very narrow.