Unpolarized EM wave: is there no electric/magnetic field? I'm not understanding what an unpolarized wave is. Does that mean there is no electric/magnetic field, or that the field is constant, i.e. frequency = 0? How can that be possible?
 A: Polarized light gets defined as the light waves that have vibrations occurring within them in a single plane. On the other hand, unpolarized light gets defined as the light waves that have vibrations occurring within them at random angles without any plane.The phase difference does not exist, and the changes in the electric field take place at random speeds.The amplitudes of vibrations are equaL.

Unpolarised light consists of components of polarized in all possible directions perpendicular to the direction of propagation of the wave.Unpolarized light consists of a mixture of light with different polarizations. If the light is traveling in the positive x-direction, this means that there are multiple directions in the yz-plane for the electric field oscillations of the various modes comprising the light.
Each of these polarization directions can be resolved into components along two mutually perpendicular directions. Thus, an unpolarised beam can be thought of as two plane polarized beams of equal magnitude perpendicular to one another. This give rise to the commonly used pictorial representation of unpolarised light wave shown in figure above. 
