Question

Unpolarised light with an intensity of $I_0=16w/m^2$ is incident on a pair of polarisers. The first polariser has its transmission axis aligned at $50^{∘}$ from the vertical. The second polariser has its transmission aligned at $20^{∘}$ from the vertical. What is the intensity (in $W/m$) of the light. When it emerges from the second polarizer.

Answer 1

Answer: 6.00

When unpolarised light emerges from $1^{\text{st }}$ polarizer the light is having intensity
$I_1=\frac{I_0}{2}=8w/m^2$
When it emerges from $2^{\text{nd }}$ polarizer
$I_2=I_1{\cos }^{2}30^{∘}$
$=(8){\left(\frac{\sqrt{3}}{2}\right)}^2=8×\frac{3}{4}$
$=6w/m^2$