State any three conditions for a sustained interference of light waves.

Explanation

Any .two. of the following :
(i) 2 Light waves must be of same wavelength or same frequency.
(ii) 2 Light waves must have either the same .Phase. or constant phase difference.
(iii) 2 source of light must be very narrow.
(iv) 2 source of light must be very close to each other.
(v) The amplitudes of 2 light waves must be same or nearly equal.
If the interfering waves are polarised, then they must have the same plane of polarisation.