An unpolarised beam of intensity $2 a^{2}$ passes through a thin polaroid. Assuming zero absorption in the polaroid,the intensity of emergent plane polarised light is

$A$ polaroid is placed at $45^o$ to an incoming light of intensity $I_0$. Now the intensity of light passing through the polaroid after polarisation would be

$A$ beam of plane polarized light falls normally on a polarizer of cross-sectional area $3 \times 10^{-4} \, m^2$. The flux of energy of the incident ray is $10^{-3} \, W$. The polarizer rotates with an angular frequency of $31.4 \, rad/s$. The energy of light passing through the polarizer per revolution 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.......$^\circ$.

Polarized glass is used for sunglasses because...

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