Question

An unpolarized light beam is incident on the polarizer of a polarization experiment, and the intensity of the light beam emerging from the analyzer is measured as $100\text{Lumen}$. Now, if the analyzer is rotated about the horizontal axis (direction of light) by ${30}^{\circ }$ in clockwise direction, the intensity of emerging light will be________ $\text{Lumen}$.

Answer 1

From Malu's law,

$I=I_o{\cos }^2\theta$

$\Rightarrow I=100\times {\cos }^2{30}^{\circ }$

$\Rightarrow I=100\times (\sqrt{3}/2{)}^2=75\text{Lumen}$