(a) How does an unpolarised light incident on a polaroid get polarised ?
Describe briefly, with the help of a necessary diagram, the polarisation of light by reflection from a transparent medium.
(b)Two polaroids ‘A’ and ‘B’ are kept in crossed position. How should a third polaroid ‘C’ be placed between them so that the intensity of polarised light transmitted by polaroid B reduces to l/8th of the intensity of unpolarised light incident on A ?
(a) When an unpolarised light falls on a polaroid, it lets only those of its electric vectors that are oscillating along a direction perpendicular to its aligned molecules to pass through it. The incident light thus gets linearly polarised.
Alternatively,
