(a) What is linearly polarised light ? Describe briefly using a diagram how sunlight is polarised
(b) Unpolarised light is incident on a polaroid. How would the intensity of transmitted light change when the polaroid is rotated ?

Explanation

(a) The light, in which vibrations of electric vectors are confined only in one particular plane perpendicular to the direction of propagation of light, is called plane polarised light.
The sunlight is ordinary unpolarised light. However, when the sunlight is scattered on encountering the molecules of Earth.s atmosphere, the scattered light as seen by an observer looking at `90^(@)` to the direction of sun is found to be plane polarised as shown in figure.
(b) The intensity of transmitted light, when unpolarised light of intensity `I_(0)` is incident on a polaroid, is `I=(I_(0))/(2)`. however, this intensity remains unchanged even when the polaroid is rotated about its own axis.