(a) Distinguish between unpolarized light and linearly polarized light. How does one get linearly polarised light with the help of a plaroid ?
(b) A narrow beam of unpolarised light of intensity `I_(0)` is incident on a polaroid `P_(1)`. The light transmitted by it is then incident on a second polaroid `P_(2)` with its pass axis making angle of `60^(@)` relative to the pass axis of `P_(1)`. Find the intensity of the light transmitted by `P_(2)`.

Explanation

Distinction between unpolarised and linearly polarized light obtainigng linearly polarized Light 1
In an unpolarised th eoscillations, of the electric field, arc in random directions, in planes perpendicular to the direction of propagation. For a polarized light, the oscillations are aligned along one particular direction.
Alternatively.
Polarized light can be distinguished, form unpolarised light when it is allowed to pass through a polaroid. Polaroid light does can sho change in its intensity remains same in case of unpolarised light.
When unpolarised light wave is incident on a polaroid, then the electric vectors along teh direction of its aligned molecules, get absorbed , the electric vector, oscillation alogn a direction perpendicular to thealigned molecules, pass thorugh. This light is called linearly polarized light.