JEE Main 2019 — Wave Optics Question with Solution

A system of three polarizers ${\mathrm{P}}_1,{\mathrm{P}}_2,{\mathrm{P}}_3$ is set up such that the pass axis of ${\mathrm{P}}_3$ is crossed with respect to that of ${\mathrm{P}}_1$ . The pass axis of ${\mathrm{P}}_2$ is inclined at ${60}^{\mathrm{o}}$ to the pass axis of ${\mathrm{P}}_3.$ When a beam of unpolarized light of intensity ${\mathrm{I}}_{\mathrm{o}}$ is incident on ${\mathrm{P}}_1,$ the intensity of light transmitted by the three polarizers is $\mathrm{I}$ . The ratio $\left({\mathrm{I}}_{\mathrm{o}}/\mathrm{I}\right)$ equals (nearly):