Subject : Applied Physics 2

Topic: Interference And Diffraction Of Light

Difficulty: High

The double slit diffraction pattern consists of central maximum which contain equally spaced interference maxima and minima on either side. In addition to these there is a central maximum with secondary maxima and minima. the intensity of which gradually decreases due to each slit. This intensity of central maximum is four times the intensity of central minimum due to a single slit. The spacing of diffraction maxima and minim depends upon the width of a slit. The spacing of interference maxima and minima depends upon (a+b) where b is the distance between two slits. The intensity of this interference maxima and minima is not constant due to overlapping of secondary maxima and minima due to diffraction and hence its intensity decreases to zero on either side of central maximum

. The interference due to two independent sources is not possible as the two sources will not emit continuous waves of the same wavelength in the same phase or with constant phase difference having same amplitude.