Question

A beam of unpolarized light of intensity $I_0$ is passed through a Polaroid $A$ and then through another Polaroid $B$ which is oriented so that its principal plane makes an angle of ${45}^{\circ }$ relative to that of $A$. The intensity of the emergent light is,

• A. $I_0$
• B. $\frac{I_0}{2}$
• C. $\frac{I_0}{4}$
• D. $\frac{I_0}{8}$
  

Answer 1

The correct option is C $\frac{I_0}{4}$


According to Malus law: Intensity of plane polarized light when passed through polaroid $B$,

$I=\frac{I_0}{2}(\cos {45}^{\circ }{)}^2=\frac{I_0}{2}\times \frac{1}{2}=\frac{I_0}{4}$

Hence, option $\left(\text{C}\right)$ is correct.