Question

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 $2\pi$.

Answer 1

When unpolarised light of intensity $I_o$ is passed from $P_1$, we get intensity of light = $I_0/2$. When this polarised light is passed from $P_2$ having ∠θ with $P_1$, we get,

I = $\frac{I_0}{2}co{s}^2\theta$

Variation of intensity with $\theta$ :