When a plane-polarised light is passed through an analyser and the analyser is rotated through $90^{\circ}$,the intensity of the emerging light

For the study of the helical structure of nucleic acids,the property of electromagnetic radiation generally used is

$A$ beam of plane polarised light of large cross-sectional area and uniform intensity of $3.3 \, W m^{-2}$ falls normally on a polariser (cross-sectional area $3 \times 10^{-4} \, m^2$) which rotates about its axis with an angular speed of $31.4 \, rad/s$. The energy of light passing through the polariser per revolution is close to ........ $\times 10^{-4} \, J$.

Unpolarised light of intensity $32 \, W m^{-2}$ passes through a combination of three polaroids such that the pass axis of the last polaroid is perpendicular to that of the pass axis of the first polaroid. If the intensity of the emerging light is $3 \, W m^{-2}$,then the angle between the pass axis of the first two polaroids is $............ \, ^{\circ}$.

The pass-axes of two polarisers were kept such that the incident unpolarised beam of intensity $I_0$ gets completely blocked. Another polariser was introduced in between these two polarisers with its pass-axis at $60^{\circ}$ with respect to the pass-axis of the first one. The output intensity would then become

Unpolarized light falls on two polarizing sheets placed one after another. What should be the angle between the pass axes of the sheets so that the final transmitted light has one-fourth the intensity of the incident light?