Brewsters angle

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Optical phenomenon discovered by Sir David Brewster (1781-1868), Scottish physicist.

When light moves between two media of differing refractive index, light which is p-polarised with respect to the interface will not be reflected from the interface at one particular incident angle, known as Brewster's angle.

It may be calculated by:

θB = arctan( n2 / n1 ) ,

where n1 and n2 are the refractive indices of the two media.

Note that, since all p-polarised light is refracted, any light reflected from the interface at this angle must be s-polarised. A glass plate placed at Brewster's angle in a light beam can thus be used as a polariser.

See also Fresnel equations.