Definition - What does Linear Polarisation mean?
Linear Polarisation is the enclosure of a magnetic field or an electric field vector to a given plane along a propagation direction. It takes place when the electromagnetic waves act on either horizontal or vertical planes. The magnetic and electric fields, in this case, are perpendicular to each other and also to the direction on which the plane wave propagates. The direction of the linearly polarised electromagnetic waves can be defined by the orientation of the electric field.
Petropedia explains Linear Polarisation
Light is considered as linearly polarised in the form of a plane wave. Light is said to be a transverse electromagnetic wave and it is usually unpolarized but all the planes of propagation are equally polarized. When light contains two plane waves with equal amplitude by altering the phase by 90 degrees, then light is polarized circularly. If the phase is not 90 degrees or the two plane waves with altering amplitude are associated in the phase by 90 degrees, then light is polarized elliptically.