An unpolarized light beam of intensity $I_0$ is passed through a first polaroid $A$ and then through a second polaroid $B$. If the principal plane of polaroid $B$ makes an angle of $45^{\circ}$ with that of $A$,find the intensity of the emerging light.

Three polarising sheets are placed co-axially. The pass axes of polaroids $2$ and $3$ make angles of $30^{\circ}$ and $90^{\circ}$ respectively with the pass axis of polaroid $1$. If $I_0$ is the intensity of unpolarised light entering sheet $1$,what is the intensity of the light emerging from sheet $3$? $(\cos 30^{\circ}=\sqrt{3} / 2, \cos 90^{\circ}=0, \cos 60^{\circ}=1 / 2)$

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.....$\%$

Unpolarised light of intensity $I_0$ is incident on a polarizer. What is the percentage of the intensity of light that gets transmitted from the polarizer (in $\%$)?

Out of the following statements,which is not correct?

The figure shows four pairs of polarizing sheets,seen face-on. Each pair is mounted in the path of initially unpolarized light. The polarizing direction of each sheet (indicated by the dashed line) is referenced to either a horizontal $x$-axis or a vertical $y$-axis. Rank the pairs according to the fraction of the initial intensity that they pass,greatest first.