Briefly explain how bright and dark fringes are formed on a screen due to the diffraction at a single slit. Hence, explain why the intensity at the bright fringes decreases sharply as their order (n) increases.

In a single slit diffraction pattern intensity and width of fringes are

Central fringe obtained in diffraction pattern due to a single slit-

(a) In Young's double slit experiment, describe briefly how bright and dark frings are obtained on the screen kept in front of a double slit. Hence obtain the expression for the fringe width. (b) The ratio of the intensities at minima to the maxima in the Young's double slit experiment is 9 : 25. Find the ratio of the widths of the two slits.

Draw a graph showing the intensity distribution of fringes due to diffraction at single slit

Alternate bright and dark fringes appear in Young's double slit experiment due to the phenomenon of