An unpolarised light is incident at an interface of two dielectric media having refractive indices of 2 (incident medium) and $2 \sqrt{3}$ (medium) respectively. To satisfy the condition that reflected and refracted rays are perpendicular to each other, the angle of incidence is ______.

JEE Main · 2026 · 24 Jan 2026 · Shift 1 · Geometrical Optics

An unpolarised light is incident at an interface of two dielectric media having refractive indices of 2 (incident medium) and

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(medium) respectively. To satisfy the condition that reflected and refracted rays are perpendicular to each other, the angle of incidence is ______.

(A) $6 0^{\circ}$ ✓ Correct
(B) $1 0^{\circ}$
(C) $3 0^{\circ}$
(D) $4 5^{\circ}$

Answer: (A)

Solution

When the reflected and refracted rays are mutually perpendicular the angle of incidence is the Brewster angle, for which

tan θ_{B} = \frac{n _{2}}{n _{1}}

. Here

\frac{n _{2}}{n _{1}} = \frac{2 3}{2} = 3

, so

tan θ_{B} = 3

. The angle of incidence is

6 0^{\circ}

JEE Main · 2026 · 24 Jan 2026 · Shift 1 · Single correct option

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