Question

Two Polaroids, $A$ and $B$ are kept with their transmission axes at an angle $\theta$ with respect to one another. If the transmitted intensity of light, $I_t=0.125I_0$,​ where $I_0$​ is the intensity of light incident on the system, then find the value of $\theta$.

• A. ${30}^{\circ }$
• B. ${75}^{\circ }$
• C. ${60}^{\circ }$
• D. ${45}^{\circ }$

Answer 1

The correct option is C ${60}^{\circ }$

As per Malu's law,

$I_t=\frac{I_0}{2}{\cos }^2\theta$

$\Rightarrow 0.125I_0=\frac{I_0}{2}{\cos }^2\theta$

$\Rightarrow {\cos }^2\theta =0.25$

$\Rightarrow \cos \theta =0.5$

$\Rightarrow \theta ={60}^{\circ }$

Hence, option $\left(C\right)$ is the correct answer.