Question

Two polarizers have their axes inclined at ${45}^{\circ }$ to each other. If unpolarized light of intensity $I$ is incident on the first poilarizer, then the intensity of transmitted light through second polarizer is:

• A. $\frac{I}{4}$
• B. $\frac{I}{2}$
• C. $I$
• D. $0$

Answer 1

The correct option is A $\frac{I}{4}$

Since through first polarizer, intensity will get halved. Hence, light incident on second polarizer will have intensity $\frac{I}{2}$. Through the second polarizer, intensity will decrease by a factor of ${cos}^2\theta$. Hence intensity after passing through second polariser is:

$\frac{I}{2}{cos}^2\theta =\frac{I}{2}{cos}^2\left({45}^0\right)=\frac{I}{4}$