The Brewster Angle
Polarisation to some degree occurs whenever light is reflected from a non – conductor of electricity. The degree of polarisation depends on the surface and angle of incidence.
For a particular anglethe beam is completely plane polarised as shown below.is known as the polarising angle or Brewster angle.
In fact for a material of refractive index n, the Brewster angle p is give by(1)
It is easily shown that the refracted and reflected beams are at right angles.
From Snell's law we getSubstituting forfrom (1) we get