A polarized light
Polarization is another property that distinguishes waves from "non–wave" material objects.
As we've seen waves come in two basic flavors: transverse and longitudinal, referring to the direction of the motion of the waving quantity with respect to the wave velocity direction. For light, or electromagnetic radiation in general, which is a transverse wave, polarization refers to the particular direction of oscillation of the electric field in the transverse plane – perpendicular to the wave velocity.
In general, the direction of the electric field may also change with time. If it changes randomly, the light is said to be unpolarized. Light from an incandescent source is unpolarized since it is produced by radiative emission from many electrons in the heated tungsten wire and there is no preferred direction along which to produce their electric field.
Polarized light from glass
There are four different ways to produce polarized light from unpolarized light: by absorption, refraction, reflection, or scattering.
An example is scattering of sunlight by molecules in the atmosphere, which gives the sky its general glow. Although direct sunlight is unpolarized, light from much of the sky is at least partially polarized by such scattering. Much of the light reflected from nonmetallic surfaces is polarized. The glare from glass or water is a good example. Except for perpendicular incidence, the reflected ray contains more vibrations parallel to the reflecting surface, whereas the transmitted beam contains more vibrations at right angles to the vibrations of reflected light.