State the conditions for constructive and destructive inter-ference of light.

Explanation

For constructive interference:
(a) Phase difference between any two waves should be integral multiple of `2pi`,i.e.,
`phi=2n pi,` where n = 0, 1, 2, ……
(b) Path difference should be equal to `(lambda)/(2pi)` times of phase difference, i.e.,
`Delta=(lambda)/(2pi)xx`Phase difference
`=(lambda)/(2pi)xx2n pi=n lambda,`
Where, n = 0, 1, 2, ...........
For destructive interference :
(a) Phase difference between two waves should be
`phi =J(2n-1)pi, ` where n = 1, 2, 3, ........
(b) Path difference should be,
`Delta =(lambda)/(2pi)xx` Phase difference
`=(lambda)/(2pi)xx(2n-1)pi`
`=((2n-1)lambda)/(2)`
Where, n = 1, 2, 3 ..........