After passing through a polariser a linearly polarised light of intensity $\mathrm{I}$ is incident on an…
After passing through a polariser a linearly polarised light of intensity $\mathrm{I}$ is incident on an analyser making an angle of $30^{\circ}$ with that of the polariser. The intensity of light emitted from the analyser will be :
$\frac{\mathrm{I}}{2}$
$\frac{\mathrm{I}}{3}$
$\frac{3 I}{4}$
$\frac{2 I}{4}$
Solution
As per Malus law, $\mathrm{I}=\mathrm{I}_0 \cos ^2 \phi$, where symbols have their usual meanings.
$\begin{aligned}
& I^{\prime}=I \cos ^2 30^{\circ} \\
& I^{\prime}=I\left(\frac{\sqrt{3}}{2}\right)^2 \\
& I^{\prime}=\frac{3 I}{4}
\end{aligned}$