Question

Unpolarized light of intensity i is incident on a system of two polarizers, a followed by b. The intensity of emergent light is i/2. If a third polarizer c is placed between a and b, the intensity of emergent light is reduced to i/3. The angle between the polarizers a and c is

Answer 1

ANSWER:

The answer is  cos θ = (2/3)^{1/4}.

Unpolarized light is the the light wave which is vibrating in more than one planes.Polarized light are the light wave is the vibrating in only single plane.The process of converting unpolarized light in to polarized light is know as Polarization.

As we have Malus Law - according to which:

I= I₀ *cos²θ

θ= angle which is made by E vector with transmission axis.

where as,

I= Intensity of transmitted light after polarization occurs .

I₀= Intensity of  incident light.

both A and B should have the  same orientation of transmission axis only so  we will have intensity of I/2 :

Now, let c makes angle θ with A then

we have : I/2 *cos² θ *cos ²θ = I/3

or  cos θ = (2/3)^{1/4}  .