(i) Distinguish between unpolarised and linearly polarised light.
(ii) What does a polaroid consist of ? How does it produce a linearly polarised light ?
(iii) Explain briefly how sunlight is polarised by scattering through atmospheric particles.

Explanation

(i) In a beam of unpolarized light, the vibrations of light vectors are in all directions in a plane perpendicular to direction of propagation. In polarized light, these vibrations are only along one direction.
(ii) Polaroids consist of long chain of molecules aligned in a particular direction. It polarizes light as it alllows only one component of light (electric vectors parallel to the pass axis) to pass through it while the other component is absorbed.
(iii) The observer receives scattered light corresponding to only one of two sets of accelerated charges i.e. electrons oscillating perpendicular to the direction of propagation.