Two light waves will interfere constructively if the path-length difference between them is a whole number.
<h3>SUPERPOSITION</h3>The principle of superposition state that, when two or more waves meet at a point, the resultant displacement at that point is equal to the sum of the displacements of the individual waves at that point.
Interference of waves can either be constructive, or destructive.
The two light waves, initially emitted in phase, will interfere constructively with maximum amplitude if the path-length difference between them is a whole number of wavelenght 1λ, 2λ, 3λ, 4λ etc
The equivalent phase differences between the waves will be 2 or 360 degrees, 4
or 720 degrees, 6
1080 degrees etc
Therefore, the two light waves, initially emitted in phase, will interfere constructively with maximum amplitude if the path-length difference between them is a whole number.
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