(a) Using the phenomenon of polarization, show, how, transverse nature of light can be demonstrated.
(b) Two polaroids `P_(1) and P_(2)` are placed with their pass axes perpendicular to each other. Unpolarised light of intensity 10 is incident on P1. A third polaroid P3 is kept in between `P_(1) and P_(2)` such that its pass axis makes an angle of `30^(@)` with that of `P_(1)`. Determine the intensity transmitted through `P_(1),P_(2) and P_(3)`.

Explanation

(a) Polaroid : It is a material which polarises light.
(i) Light waves are transverse in nature and the electric field associated with a propagating light wave is always at `90^(@)` right angles to the direction of the propagation of the wave. If a light wave is incident on the polaroid. the electric vectors along the direction of the molecules get absorbed.
(ii) The light wave gets linearly polarised with the electric vector. oscillating along a direction perpendicular if an unpolarised light wave.
`(b)(i)" "I_(1)=(I_(0))/(2)`
`(ii)" "I_(3)=I_(1)cos^(2)30`
`=I_(1)xx(3)/(4)((I_(0))/(2))xx((3)/(4))=(3)/(8)I_(0)`.
`(iii) " "I_(2)=I_(3)cos^(2)60`
`=((3)/(8)I_(0))xx(1)/(4)=(3)/(32)I_(0)`.
`[theta=90^(@)-30^(@)=60^(@)]`