Question

Two polarising sheet have their polarising directions parallel so that the intensity of the transmitted light is maximum. Through what angle must the either sheet be turned if the intensity is to drop by one-half?

Answer 1

Here, I = \(\frac{I_0}{2}\)

Using Malus law,, 

I = I₀ cos² θ

\(\frac{I_0}{2}\) = I₀ cos² θ

cos θ ± \(\frac{1}{\sqrt2}\)

θ = ± 45°, ± 135°