Question

A single slit diffraction pattern is observed. What is the ratio of the intensity of different maxima’s observed? What is ratio of radii of different subsidary maxima’s observed.

Answer 1

Let I₀ , I₁ , I₂ ,........ be the intensity of centeral maximum, first, second,....... subsidary maxima’s observed. Very approximately

This because at centeral maximum all secondary wavelets from plane of slit undergo constructive interference. At first subsidary maximum nearly 1^rd/3 of secondary wavelets do not undergo distructive interference. At second maximum nearly 1^th/5 of secondary wavelets from plane of slit donot undergo destructive interference with one another and so on.

The radii of subsidary maxima’s are given by