When a polaroid sheet is rotated between two crossed polaroids,then the transmitted light intensity will be maximum for a rotation of: (in $^{\circ}$)

The intensity of incident unpolarized light on a polaroid is $I_1$ and the intensity of emergent polarized light from this polaroid is $I_2$. The relation between $I_1$ and $I_2$ is $.......$

$A$ beam of plane polarised light of large cross-sectional area and uniform intensity of $3.3 \, W m^{-2}$ falls normally on a polariser (cross-sectional area $3 \times 10^{-4} \, m^2$) which rotates about its axis with an angular speed of $31.4 \, rad/s$. The energy of light passing through the polariser per revolution is close to ........ $\times 10^{-4} \, J$.

An unpolarised beam of intensity $I_{0}$ falls on a polaroid. The intensity of the emergent light is

Statement-$1$: The blue part of the sky is clearly visible through a calcite crystal. The intensity of the transmitted light changes as the crystal is rotated.
Statement-$2$: Light from the sky is due to the scattering of sunlight by particles in the atmosphere.

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