14. Interference Of Light

In physics, interference is a phenomenon in which two waves superimpose to form a resultant wave of greater or lower or the same amplitude. When two light waves from different coherent sources meet together, then the distribution of energy due to one wave is distributed by the other. This modification in the distribution of light energy due to super-position of two light waves is called the 'interference of light'. There are the following two conditions for the interference of two light waves and they are :

> The sources of the waves must be coherent, which mean they emit identical waves with a constant phase difference.

> The waves should be monochromatic means they should be of a single wavelength.

it was done by using Young's Double slit experiment method. When two waves interact, the principle of superposition says that the resulting wave function is the sum of the two individual wave functions. This phenomenon is generally described as interference. Usually there are two types of interferences :-

>> Constructive interference

It occurs when the wave amplitudes reinforce each other, building a wave of even greater amplitude. That means if crest of one wave overlaps or falls on the crest of another wave, then the amplitudes gets added up to its maximum amplitude.

>> Destructive interference

It occurs when the wave amplitudes opposes each other, resulting in a wave of reduced amplitude. That means the crest of one wave overlaps the trough of another wave or the waves do not have the same displacement, then the amplitude effects get reduced and the waves will get out of phase.