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 $W/m^2$)

Three polaroid sheets are co-axially placed as indicated in the diagram. Pass axes of the polaroids $2$ and $3$ make $30^{\circ}$ and $90^{\circ}$ with the pass axis of polaroid sheet $1$. If $I_0$ is the intensity of the incident unpolarised light entering sheet $1$,the intensity of the emergent light through sheet $3$ is

Polarised glass is used in sunglasses because

When an unpolarized light of intensity $I_0$ is incident on a polarizing sheet,the intensity of light which does not get transmitted is

When unpolarized light of intensity $I_0$ is incident on a polarizing sheet,the intensity of light that does not pass through is:

$A$ system of three polarizers $P_1, P_2, P_3$ is set up such that the pass axis of $P_3$ is crossed with respect to that of $P_1$. The pass axis of $P_2$ is inclined at $60^{\circ}$ to the pass axis of $P_3$. When a beam of unpolarized light of intensity $I_0$ is incident on $P_1$,the intensity of light transmitted by the three polarizers is $I$. The ratio $(I_0/I)$ equals (nearly)