Discussion Forum

Two polaroids are kept crossed on top each other. If one of them is rotated an angle 60°, the percentage of incident light now transmitted through the system is 

Answer:

Explanation:

Let the intensity of unpolarised light be I₀. so the intensity of first polaroid   is  $\frac{I_{0}}{2}$. On rotating  through 60° , the intensity of light from second polaroid

$I=\frac{I_{0}}{2}(\cos 60)^{2}=\frac{I_{0}}{2}\frac{I}{4}=\frac{I_{0}}{8}=0.125 I_{0}$

 $\therefore$ percentage of incident light transmitted through the system=12.5%