Unpolarized Light
Electromagnetic waves emmitted by the sun or a regular light bulb are randomly polarized, or unpolarized. When light is unpolarized, the E vector is always perpendicular to the direction of travel, but it changes directions randomly.
If the vibration direction of unpolarized light is constrained so that it is not uniformly distributed around the direction of propogation, it becomes polarized. There are three different types of polarization; plane polarization, circular polarization, and elliptical polarization. For our purposes we will only consider plane polarization.
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Courtesy of Peter Whitehead, James Cook University http://www.jcu.edu.au/~glpww/EA2001/Light/Light.html
The plane containing the electric field vectors is called the plane of oscillation. For example, if the wave travels in the z-direction, the electric field oscillates in the x-y plane. When light is plane polarized, the light wave is a simple sine wave with the vibration direction in the plane of oscillation.
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