$A$ plane polarized light is incident normally on a tourmaline plate. Its $\vec{E}$ vectors make an angle of $60^{\circ}$ with the optic axis of the plate. Find the percentage difference between initial and final intensities. (in $\%$)

Two polaroids are kept crossed to each other. Now one of them is rotated through an angle $45^{\circ}$. The percentage of incident light now transmitted through the system is ......$\%$

The figure shows a glass plate placed vertically on a horizontal table. $A$ beam of unpolarised light falls on its surface at the polarising angle of $57^\circ$ with the normal. The electric vector in the reflected light on screen $S$ will vibrate with respect to the plane of incidence in a:

Two polaroids have their polarizing directions parallel so that the intensity of the transmitted light is maximum. The angle through which either polaroid must be turned so that the intensity of the transmitted light is dropped to one-half of the previous transmitted intensity is $.....^\circ$.

Two polaroids $A$ and $B$ are placed perpendicularly in the path of a beam of unpolarized light. In between these two,a third polaroid $C$ is placed at an angle of $30^o$ with that of $A$. The percentage of intensity of incident unpolarized light that emerges from $B$ is ........$\%$.

Two beams,$A$ and $B$,of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam $A$ has maximum intensity (and beam $B$ has zero intensity),a rotation of the polaroid through $30^{\circ}$ makes the two beams appear equally bright. If the initial intensities of the two beams are $I_A$ and $I_B$ respectively,then $\frac{I_A}{I_B} = $