Duduli

It is an optical device made from calcite crystal & is used in many optical instruments for producing & analysing plane polarized light. It derives its name from its inventor William Nicol who first designed it 1828. It is based on the phenomenon of double refraction when an unpolarized light ray passes through a calcite crystal it splits into 2 refracted rays i.e o-ray & E-ray. The vibrations of E-ray are in the plane of paper while those of o-ray are perpendicular to plane of paper. Both these rays are plane polarized & are perpendicular to each other. For obtaining only single polarized beam, we should eliminate the other beam. Nicol prism is made in such a way that it eliminates o-ray by TIR & only E-ray comes out of the prism.

Malus's law states that “ intensity of polarized light transmitted through a polarizer is proportional to the square of cosine of the angle between the plane of polarization of the light and the transmission axis of the polarizer”.

Optically inactive substances acquire the ability of rotating the plane of polarization of light when they are subjected to a magnetic field, parallel to propagation direction. Michael Faraday discovered this effect and hence it is called Faraday effect. This effect occurs in most optically transparent dielectric materials (including liquids) when they are subject to strong magnetic fields.

When some electromagnetic wave is incident on a scatterer atom, whose size is comparable to wave length of wave, then due to the electric vector of the incident wave the atom starts oscillating.This oscillating atom(acting as small dipole) itself emitts radiations. But the reemission of e.m. wave by the oscillating dipole is such that it emitts e.m. waves in all directions except in the direction of oscillation.This fact can be used for polarization of light.

Answer:- Photoelasticity is an experimental method to determine stress distribution in various engineering components.The method is mostly used in cases where mathematical methods become quite cumbersome.

Answer:- A retarder is a uniform plate of birefringent material whose optic axis lies in the plane of the plate.Retarders are called quarter-wave plates, half-wave plates and full-wave plates depending  on their action.

Answer:- It states that intensity of polarized light transmitted through a polarizer is proportional to the square of cosine of the angle between the plane of polarization of the light and the transmission axis of the polarizer.