Physics - Wave Optics Question with Solution | TestHub

Intensity of unpolarized light = $I_0$

Intensity of light after passing through the first polaroid $P_1$ is:
$I_1=\frac{I_0}{2}$

The angle between the pass axis of $P_1$ and $P_2$ is ${\theta }_1=60^{\circ }$. According to Malus's law, the intensity of light after passing through $P_2$ is:
$I_2=I_1{\cos }^2(60^{\circ })=\frac{I_0}{2}\times {\left(\frac{1}{2}\right)}^2=\frac{I_0}{8}$

The angle between the pass axis of $P_1$ and $P_3$ is $90^{\circ }$. Therefore, the angle between the pass axis of $P_2$ and $P_3$ is:
${\theta }_2=90^{\circ }-60^{\circ }=30^{\circ }$

The intensity of light after passing through $P_3$ is:
$I_3=I_2{\cos }^2(30^{\circ })=\frac{I_0}{8}\times {\left(\frac{\sqrt{3}}{2}\right)}^2=\frac{I_0}{8}\times \frac{3}{4}=\frac{3I_0}{32}$

Answer: $\frac{3{\mathrm{I}}_0}{32}$