Question

Unpolarised light is passed through a polarised $P_1$. When this polarised beam passes through another polarised $P_2$ 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 $2\pi$.

Answer 1

Here,

1. $E$ is unpolarized light passes through a polarizer $P_1$ and again this polarized light pass through a polarizer $P_2$, the pass axis of $P_2$ makes angle $\theta$ with the pass axis of $P_1$,
   
2. Expression for the polarised beam passing through the $P_2$ is $I=I_{o}co{s}^2\theta ,$Here $I=$Intensity of unpolarised light, $I_o=$Intensity of polarised light, and $\theta$ is the angle between Polarizer $P_1$ and $P_2$. This is known as malus' law.