Question

Distinguish between linearly polarised and unpolarised light.

Answer 1

The transverse waves of light can and are oriented $360$ degrees around the direction of photon travel. If we look down the direction of travel of a beam of light, the transverse waves from that beam would totally encircle the axis of that beam. When these transverse waves of light are oriented completely around the direction of the light, we call that "unpolarized" light.
This is actually a misnomer. In fact that kind of light is omni polarized, i.e. it is polarized in all angles around the light beam. But if we pass the omni poloarized or unpolarized beam through a linearly polarized piece of glass, all but the transverse waves oriented in the same angle as the glass will be blocked out. There will be but one angle of transverse waves around the beam allowed through the glass. And that's the linearly polarized light.