Question

Polarized light passes through a polarizer, and only 20% gets through. find the angle between the light's electric field and the polarizer's transmission axis

Answer 1

answer for this question is 63 degrees

Answer 2

The angle between the light’s electric field and the polarizer’s transmission office is $\bold{\theta=\cos ^{-1} \sqrt{0.2}}$

SOLUTION:

The light passing through is a polarized light, so Malus law is applicable over here

$I=I_{0} \cos ^{2} \theta$

Only 20 % of the light gets polarized so  

$I=20 \% I_{0}$

I=0.2 I_{0}  

Substituting in Malus law

$0.2 I_{0}=I_{0} \cos ^{2} \theta$

$0.2=\cos ^{2} \theta$

$\theta=\cos ^{-1} \sqrt{0.2}$

This will be the required angle between the electric field and the polarizer transmission axis.

In the above Malus relation  

I is the lights intensity that is thoroughly passing and I_{0} is the lights intensity that is incident on the polarizer.