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 ........$\%$.

$A$ polariser is used to

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

$A$ polarizer-analyser set is adjusted such that the intensity of light coming out of the analyser is $10 \%$ of the original intensity. Assuming that the polarizer-analyser set does not absorb any light,the angle by which the analyser needs to be rotated further to reduce the output intensity to zero is.....$^o$

$A$ polaroid $(I)$ is placed in front of a monochromatic source. Another polaroid $(II)$ is placed in front of this polaroid $(I)$ and rotated until no light passes. $A$ third polaroid $(III)$ is now placed in between $(I)$ and $(II)$. In this case,will light emerge from $(II)$? Explain.

The specific rotation of a sugar solution is $0.01 \ SI$ units. $A$ $200 \ kg/m^3$ solution of impure sugar is taken in a polarimeter tube of length $0.25 \ m$,and an optical rotation of $0.4 \ rad$ is observed. The percentage of purity of sugar in the sample is.....$\%$