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 ${\mathit{P}}_1$. When this polarised beam passes through another polaroid ${\mathit{P}}_2$ and if the pass axis of ${\mathit{P}}_2$ makes angle $\mathit{\theta }$ with the pass axis of ${\mathit{P}}_1$, then write the expression for the polarised beam passing through ${\mathit{P}}_2$. Draw a plot showing the variation of intensity when $\mathit{\theta }$ varies from 0 to $2\mathit{\pi }$.