Unpolarised light is incident on a plane glass surface. For which angle of incidence are the reflected and the refracted rays perpendicular to each other? (Refractive index of glass =1.5)

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(1) 57°. Given: unpolarised light on glass of μ=1.5, with the reflected and refracted rays at right angles. Idea: with the reflected ray at i and the refracted ray at r from the normal, the angle between them is 180°-(i+r). Setting that to 90° gives i+r=90°, and substituting r=90°-i in Snell's law gives Brewster's law, tan iₚ=μ. iₚ=tan⁻¹1.5. tan⁻¹1.5=56.3°. iₚ≈57°.

Unpolarised light is incident on a plane glass surface. For which angle of incidence are the reflected and the refracted rays perpendicular to each other? (Refractive index of glass =1.5)

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