Question

State two points of difference between the interference patterns obtained in Young’s double slit experiment and the diffraction pattern due to a single slit.

Give two points of difference between an interference pattern due to a double slit and a diffraction pattern due to a single slit.

Answer 1

The two differences between the interference patterns obtained in Young’s double slit experiment and the diffraction pattern due to a single slit are as follows:

1. The fringes in the interference pattern obtained from diffraction are of varying width, while in the case of interference, all are of the same width.
2. The bright fringes in the interference pattern obtained from diffraction have a central maximum followed by fringes of decreasing intensity, whereas in the case of interference, all the bright fringes are of equal width.

Answer 2

Points	Interference	Diffraction
Origin:	It is produced by the superposition of light from two coherent sources (double slit).	It is produced by the superposition of wavelets from different parts of the same slit (single slit).
Fringe width and intensity:	The fringes are equally spaced and of nearly equal intensity (except due to envelope effects).	The central maximum is widest and brightest; secondary maxima are weaker and not equally spaced. Intensity decreases rapidly for higher orders.