(a) What is linearly polarized light? Describe briefly using a diagram how sunlight is polarised.

(b) Unpolarized light is incident on a Polaroid. How would the intensity of transmitted light change when the polaroid is rotated? 

a) When an unpolarized light is transmitted through a polarizer, only one component is along the direction of propagation. This transmitted light is called as linearly polarized light.

The incident sunlight is unpolarized. Molecule in air acts as a dipole radiator. When the sunlight falls on a molecule, dipole molecule does not scatter energy along the dipole axis; however the electric field vector of light wave vibrates just in one direction perpendicular to the direction of the propagation. The light wave having direction of electric field vector in a plane is said to be linearly polarized.

b) When unpolarized light is incident on a Polaroid, the transmitted light has electric vibrations in the plane consisting of Polaroid axis and direction of wave propagation.



The plane of polarization will change when the Polaroid is rotated. However, the intensity of transmitted light will remain unchanged.