Chapter 48: Problem 14

Question: Light travelling in water of refractive index n₁ = 1.33 is incident on a plate of glass of refractive index n₂ = 1.53. At what angle of incidence is the reflected light completely linearly polarized?

Solution: We know from our lectures, that Brewsters angle can be simply derived from

$$n_1\sin\theta_1~=~n_2\sin\theta_2~=~n_2\cos\theta_1$$

because the reflected light will be $100\%$ polarized if it is reflected at an angle 90^o to the refracted light. Hence, Brewsters angle is

$$\tan\theta_1~=~{n_2\over n_1}~=~{1.53\over 1.33}$$

giving $\theta~=~49^o$, as measured from the normal.