Question

An unpolarised plane light wave intensity 10w/cm^2 passes through two nicols with the principal of section at 30° to each other .Calculate the intensity of the transmitted wave

Answer 1

Answer:

3.75 Wb/cm2

Explanation:

Let Io=10wb/cm2

after 1st polarizer:- I =Io/2

I = 5wb/cm2

after 2nd nicol prism

IFinal = I*Cos30*Cos30

IFinal = 3.75 Wb/cm2

Answer 2

Given:

The intensity of the unpolarised plane light wave = 10 W/cm²

The angle between the two prisms = 30°

To Find:

The intensity of the transmitted wave

Solution:

The intensity of the transmitted wave is 3.75 W/cm².

When an unpolarised plane light passes through Nicole's prisms, its intensity gets reduced.

The final intensity of the transmitted light is given using the Malus Law.

I' = Iο cos²θ

So when the light passes through the first prism, it acts as a polarizer.

We know that if the initial intensity of incident light is I, after passing through a polarizer it becomes I/2.

Substituting the values,

I/2 = 10/2 = 5 W/cm²

Further after passing through the second prism that acts as an analyzer, using Malus Law, the transmitting intensity will be I' = I/2 cos²30

Substituting the values,

I' = 5 cos² 30

= 5 X 3 / 4

= 15/4

= 3.75 W/cm²