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

According to Malus's law,
      
I = I₀cos²Θ

Here, 

I is the intensity of light that gets through,

I₀ is the intensity incident on polarizer  and Θ is the angle between light's electric field and the polarzer's transmission axis.
 
Here,

I = 20% of I₀ = 0.2I₀

So,

0.2I₀ = I₀cos²Θ
⇒ 0.2 = cos²Θ
⇒ Θ = cos⁻¹(√0.2)