Question

A narrow beam of unpolarised light of intensity $I_o$ is incident on a Polaroid $P_1$. The light transmitted by it is then incident on a second polaroid $P_2$ with its pass axis making angle of ${60}^0$ relative to the pass axis of $P_1$. Find the of intensity of the light transmitted by $P_2$ .

Answer 1

After passing from P${}_1$, the intensity of the light will be $\frac{I_0}{2}$

Now after passing from P${}_2$, the new intensity of the light will be $\frac{I_0}{2}{\cos }^2\theta$.

Intensity of light after transmission from Polaroid:

$I=I{\cos }^2\theta =\frac{I_0}{2}\times (\cos 60°{)}^2=\frac{I_0}{2}\times {\left(\frac{1}{2}\right)}^2=\frac{I_0}{8}$