CBSE Class 12-science Answered

Young double slit experiment:

A train of plane light waves is incident on a barrier containing two narrow slits separated by a distance 'd'. The widths of the slits are small compared with wavelength of the light used, so that interference occurs in the region where the

light from S₁ overlaps that from S₂.

At the point where two wave crests or troughs superimpose, the intensity is maximum and at the point where the crest of one wave superimpose the trough of other wave the intensity is minimum. A series of alternately bright and dark bands can be observed on a screen placed in this region of overlap.

The variation in light intensity along the screen near the centre O shown in the figure

Here all bright and dark fringes are of equal width.