$A$ calcite crystal is placed over a dot on a piece of paper and rotated. On seeing through the calcite,one will see:

$A$ polaroid is placed at $45^o$ to an incoming light of intensity $I_0$. Now the intensity of light passing through the polaroid after polarisation would be

When light of an unknown polarization is examined with a polaroid, it is found to exhibit maximum intensity $I_0$ along the $y$-axis and minimum intensity $\frac{2I_0}{3}$ along the $x$-axis. The intensity transmitted through a polaroid with pass axis at $45^{\circ}$ to the $y$-axis (in the $x$-$y$ plane) is:

Define unpolarized light and polarized light.

The angle between the axes of a polariser and an analyser is $45^{\circ}$. If the intensity of the unpolarized light incident on the polariser is $I$,then the intensity of the light emerged from the analyser is

Polarised glass is used in sunglasses because