Question

Unpolarized light of intensity I passes through an ideal polarizer A. Another identical polarizer $B$ is placed behind $A$. The intensity of light beyond $B$ is found to be $\frac{I}{2}.$ Now another identical polarizer $C$ is placed between $A$ and $B$. The intensity beyond $B$ is now found to be $\frac{I}{8}.$ The angle between polarizer $A$ and $C$ is :

• A. ${45}^{\circ }$
• B. ${60}^{\circ }$
• C. $0^{\circ }$
• D. ${30}^{\circ }$

Answer 1

The correct option is A ${45}^{\circ }$


$$\begin{array}{c}\frac{I}{2}{\cos }^4\theta =\frac{I}{8}\\ {\cos }^2\theta =\frac{1}{2}\\ \cos \theta =\frac{1}{\sqrt{2}}\Rightarrow \theta ={45}^{\circ }\end{array}$$