A source of light is placed in front of a screen. Intensity of light on the screen is I. Two Polaroids P_1 and P_2 are so placed in between the…

A source of light is placed in front of a screen. Intensity of light on the screen is I. Two Polaroids $\displaystyle \mathrm{P}_1$ and $\displaystyle \mathrm{P}_2$ are so placed in between the source of light and screen that the intensity of light on screen is $\displaystyle \mathrm{I} / 2$. $\displaystyle \mathrm{P}_2$ should be rotated by an angle of \_\_\_\_ (degrees) so that the intensity of light on the screen becomes $\displaystyle \frac{3 \mathrm{I}}{8}$.