Non-Polarized EM Wave: Example & Explanation

[fluidistic]

Can someone give me an example of a non polarized EM wave? I've heard that a light bulb would produces EM waves not polarized because the E fields of each waves aren't in the same direction. This I can understand. But in the case of a single EM wave, how do one gets a non polarized wave? I don't see how it's possible. What would that mean? That the E field's direction changes randomly when the time increases? How can we produce such a wave? But if the E field isn't continuous, it wouldn't satisfy Maxwell's equations?

I'm confused.

 

[Andy Resnick]

I prefer the term 'randomly polarizaed' rather than 'unpolarized', becasue at any given instant, the electric field has a definite direction. That direction may be orderly (fully polarized light) or randomly fluctuate (randomly polarized).

Light from an incandescent light bulb, sunlight, fluorescent light... all those are randomly polarized sources.

Scattering processes will 'depolarize' light as well- passing highly polarized light though a rotating ground glass sheet will produce randomly polarized light.

 

[Meir Achuz]

Light from a single atom is polarized. Light from 10^23 atoms is randomly polarized, which is the same as unpolarized.