What are partially polarised light ?

Explanation

Plane polarised: If the vibrations of a wave are peresent in only one direction on a plane perpendicular to the direction of propagation of the wave is said to be polarised or plane polarised light.
Unpolarised: A transverse wave which has vibrations in all directions in a plane perpendicular to the direction of propagation is said to the unpolarised light.
Partially polarised light: If the intensity of light varies between maximum and minimum for every rotation of `90^(@)` of the analyser, the light is said to be partially polarised light.