I cos f ( . ) In equation ( . ) if the phase difference, ϕ = , ± π , ± π . .
. , it corresponds to the condition for maximum intensity of light called constructive interference . The resultant maximum intensity is, a a I I max max ∝ ( . ) - - - - Unit wave optics EXAMPLE .
Two light sources have intensity of light as I . What is the resultant intensity at a point where the two light waves have a phase difference of π / ? Solution Let the intensities be I . The resultant intensity is, I = I cos ( ϕ / ) Resultant intensity when, f p / , is cos / p