Draw the intensity pattern for single slit diffraction and double slit interference. Hence, state two differences between interference and diffraction patterns. OR Unpolarised light is passed through a polaroid $P_1$. When this polarised beam passes through another polaroid $P_2$ and if the pass axis of $P_2$ makes angle $\theta$ with the pass axis of $P_1$, then write the expression for the polarised beam passing through $P_2$. Draw a plot showing the variation of intensity when $\theta$ varies from 0 to $2\pi$.