Brewsters Law Formula

When unpolarized light of a certain wavelength is incident upon the surface of a transparent substance it experiences maximum plane polarization at the angle of incidence whose tangent is the refractive index of the substance.

The specific value of angle of incidence at which the reflected light is completely polarized is called the polarizing angle

Brewster's law


  • µ is the refractive index of the medium
  • ip is the polarizing angle

Solved Examples

Problem 1: A certain polarizer has a refractive index of 1.33. Find the polarization angle and angle of refraction?


Refractive index of the polarizer = 1.33

The Brewster’s law is μ = tan ip

ip = tan−1 (1.33)

ip = 53.06

Now, Angle of refraction

It is given that ip + ir = 90 degrees

Thus, angle of refraction or ir = 90 – 53.06

Angle of refraction = 36.94

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