The tourmaline crystal:

An unpolarised light of intensity $I$ is passed through two polaroids kept one after the other with their planes parallel to each other. The intensity of light emerging from the second polaroid is $\frac{I}{4}$. The angle between the pass axes of the polaroids is (in $^{\circ}$)

Discuss the intensity of transmitted light when a polaroid sheet is rotated between two crossed polaroids.

How can it be determined whether a given light is unpolarized,plane-polarized,or partially plane-polarized?

$A$ source of light is placed in front of a screen. The intensity of light on the screen is $I.$ Two Polaroids $P_{1}$ and $P_{2}$ are placed between the source of light and the screen such that the intensity of light on the screen is $I/2.$ By what angle (in degrees) should $P_{2}$ be rotated so that the intensity of light on the screen becomes $3I/8?$

Plane polarised light is passed through a polaroid. On viewing through the polaroid,we find that when the polaroid is given one complete rotation about the direction of the light,one of the following is observed: