$A$ polariser is used to

Two polaroids are placed in the path of an unpolarised light beam of intensity $I_0$ such that no light is emitted from the second polaroid. If a third polaroid,whose polarisation axis makes an angle $\theta$ with that of the first polaroid,is placed between the polaroids,then the intensity of light emerging from the last polaroid is

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 $W/m^2$)

When unpolarized light of intensity $I_0$ is incident on a polarizer,what will be the intensity of the light that does not pass through it?

$A$ mixture of plane-polarized and unpolarized light falls normally on a polarizing sheet. On rotating the polarizing sheet about the direction of the incident beam,we find that the ratio of maximum to minimum transmitted intensity is $4$. Find the ratio of the intensities $I_P$ and $I_0$,respectively,of the polarized and unpolarized components in the incident beam.

The relation $I = I_0 \cos^2 \theta$ is known as (where $I_0$ is the intensity of incident light on the analyser,$I$ is the intensity of emergent light from the analyser,and $\theta$ is the angle between the plane of polarization and the axis of the analyser):