Question

What do you mean by interference of light? Discuss necessary conditions for interference.

Answer 1

Interference is the phenomenon of superimposition of two or more waves having same frequency emitted by coherent sources such that amplitude of resultant wave is equal to the sum of the amplitude of the individual waves. The amplitude of resultant wave can either be larger or smaller than of individual waves depending on whether the interference is constructive or destructive.
For interference to take place, the light emitting sources must be coherent i.e. the phase difference between the two sources must remain constant with time and the frequencies of emitted light must also be equal.