Interference of light:- “It is the phenomena of redistribution of light energy due to superposition of light waves from two coherent sources.”

Explanation:-

For a single source of light, the distribution of light energy is uniform in the surrounding medium. But for two coherent sources, the distribution of light does not remain uniform.

At some points where crest of one wave falls on the crest of other, resultant amplitude is maximum and thus the, intensity of light becomes maximum. At points, where the crest of one wave fall on the trough of other, resultant amplitude is minimum and thus the intensity is minimum.

Types of interference:-

1. Constructive interference:-

When light waves from two coherent sources superimpose, then at some points on the screen the resultant intensity of light is maximum. Such type of interference is called as constructive interference.

2. Destructive interference:-

When light waves from two coherent sources superimpose, then at some points on the screen, the resultant intensity of light is minimum. Such type of interference is called as destructive interference.

Phase difference and path difference:-

It phase difference between two waves is 2π, path difference between them = λ

It phase difference between two waves is 1, path difference between them = λ/2π

 It phase difference between two waves is φ, path difference between them = λ/2π x φ