Question

What do you mean by plane polarized light?how does the phenomena decide that light waves are transverse?

Answer 1

Polarization" is when the orientation of a transverse wave is restricted to a particular plane. In other words, the very definition of "polarization" requires a transverse wave.
A plane is a two dimensional shape. The vibrations of a transverse wave are perpendicular to the direction of travel, so combining the two motions of the travel and vibrations leads to a 2D result. Transverse waves can therefore be confined to a plane – i.e they can be polarised.
The vibrations of longitudinal waves are parallel to the direction of travel. Combining these motions leads to a 1D result. Longitudinal waves cannot therefore be confined to a plane – i.e they cannot be polarised.