# Polarized Light

Essay by avioletfluidHigh School, 12th grade March 2004

The Oxford dictionary defines polarize as to confine similar vibrations of (light waves, etc) to a single direction or plane.

Polarized light is light that's had its electric vector reflected in an orderly and predictable way. The difference between polarized light and unpolarized light is that unpolarized light is reflected in a random way, rather than organized, it is also more difficult to produce fully unpolarized light than completely polarized. It is the electric vector, not the magnetic vector of a light wave that produces the effects of polarization, in stating that, we can say that the electric vector of a light wave can be identified as the light vector.

Humans are unable to detect polarization, so The Polaroid Corporation invented polaroid sunglasses. These sunglasses enable the wearer to notice the light source that a rainbow is coming from. The naked eye cannot see this.

One of the simplest ways of producing polarized light is by reflecting light off a surface that doesn't conduct electricity.

At a specific angle of reflection the electric vector becomes zero. The light that is reflected is polarized at right angles to the surface. E. Malus discovered this in 1808. Brewster's law states, at the polarizing angle the refracted ray makes an angle of 90ÃÂº with the reflected ray. Combining this, with Snell's law of reflection (n1 sin1 = n2 sin2) we can state this equation:

tan i = n

Where i is the angle of incidence, and n is the refractive index. This equation gives an easy way of measuring refractive indices.

The law of Malus

The law of Malus states that if linearly polarized light falls on a surface that doesn't conduct electricity at 90ÃÂº (Brewster's Angle) then the reflectivity of the surface depends on the angle between the electric vector,