Two polaroid sheets are placed one over the other with their axes inclined to each other at $30^{\circ}$. The ratio of the intensity of the unpolarised incident light and the polarised emergent light is

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

Light passes successively through two polarimeter tubes,each of length $0.29 \ m$. The first tube contains a dextrorotatory solution of concentration $60 \ kg/m^3$ and specific rotation $0.01 \ rad \ m^2/kg$. The second tube contains a laevorotatory solution of concentration $30 \ kg/m^3$ and specific rotation $0.02 \ rad \ m^2/kg$. The net rotation produced is.......$^\circ$.

Indicate the signals used for unpolarised,polarised,and partially polarised light.

$A$ point source $S$ emits unpolarized light uniformly in all directions. At two points $A$ and $B$,the ratio $r = I_A / I_B$ of the intensities of light is $2$. If a set of two polaroids having $45^{\circ}$ angle between their pass-axes is placed just before point $B$,then the new value of $r$ will be.

Two polaroids are placed in the path of an unpolarised 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 the polarisation axis of the first polaroid,is placed between these polaroids,then the intensity of light emerging from the last polaroid will be: