Three identical polaroids $P_1, P_2$ and $P_3$ are placed one after another. The pass axis of $P_2$ and $P_3$ are inclined at an angle of $60^{\circ}$ and $90^{\circ}$ with respect to the axis of $P_1$. The source has an intensity $I_0 = 256 \ W/m^2$. Find the intensity of light at point $O$. (in $W/m^2$)

Two polaroids have their polarizing directions parallel so that the intensity of the transmitted light is maximum. The angle through which either polaroid must be turned so that the intensity of the transmitted light is dropped to one-half of the previous transmitted intensity is $.....^\circ$.

When a plane-polarised light is passed through an analyser and the analyser is rotated through $90^{\circ}$,the intensity of the emerging light

Three identical polaroids $P_1, P_2$ and $P_3$ are placed one after another. The pass axis of $P_2$ and $P_3$ are inclined at an angle $60^{\circ}$ and $90^{\circ}$ with respect to the axis of $P_1$. The source has an intensity $I_0$. What is the intensity of transmitted light through $P_3$? $\left(\cos 60^{\circ}=0.5, \cos 30^{\circ}=\frac{\sqrt{3}}{2}\right)$

Unpolarized light of intensity $32 \ W m^{-2}$ passes through three polarizers such that the transmission axes of the first and second polarizers make an angle of $30^\circ$ with each other,and the transmission axis of the last polarizer is crossed with that of the first. The intensity of the final emerging light will be.......$W m^{-2}$

Four polaroids are placed such that the optic axis of each is inclined at an angle of $30^{\circ}$ with the optic axis of the preceding one. If unpolarised light of intensity $I_0$ falls on the first polaroid,the intensity of light transmitted from the fourth polaroid is $[\cos 30^{\circ} = \sqrt{3} / 2]$.