(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

When light is passed through a polaroid, its intensity is reduced to half then it is polarised light. If the intensity of light does not change on the rotation of the polaroid, the light is unpolarised.
When the intensity of transmitted light change on rotation of the polaroid, light is polarised.