Question

Unpolarized light passes through a combination of two ideal polarizers. The transmission axes of the first polarizer and the second polarizer are at 30.0° to each other. What percentage of the original light gets through the combination?

Answer 1

Answer:

62.5 %

Explanation:

Let the initial intensity of unpolarized light is Io.

After first polariser the intensity of light becomes I'.

So, $I' = \frac{I_{0}}{2}$

Now it passes through another polariser. The angle between the first polariser and the second polariser is given by Ф. The intensity is I''.

According to the law of Malus

$I'' = I' Cos^{2}\phi$

Here, Ф = 30 degree

$I'' = \frac{I_{0}}{2} Cos^{2}30=0.375I_{0}$

The percentage change in the intensity is given by

$\frac{I_{0}-I''}{I_{0}}\times 100=\frac{I_{0}-0.375I_{0}}{I_{0}}\times100$

= 62.5 %