Question

Two polarisers are Oriented with transmission planes making an angle of 60° . The percentage of unpolarised light that passes through the system is ?​

Answer 1

Hello there !

When the light is incident with intensity (Io)  on the first polarizer then it becomes polarized and its value becomes half:

 $I_1 = \frac{I_0}{2}$

Now , when the light with intensity Io/2 falls on the second polarizer making an angle of 60° then by applying Mallus law , the intensity of the light becomes:

$I_2 = I_0Cos^2$θ

$I_2 = \frac{I_0}{2} * \frac{1}{4}$

$I_2 = \frac{I_0}{8}$

Now, for finding percentage :

$\frac{I_0/8}{I_0} * 100 = 12.5 %$ %

So , the percentage of unpolarised light that passes through the system is 12.5%

Happy learning!