JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Geometrical Optics

Light enters from air into a given medium at an angle of

4 5^{\circ}

with interface of the air-medium surface. After refraction, the light ray is deviated through an angle of

1 5^{\circ}

from its original direction. The refractive index of the medium is :

(A)1.732
(B)1.333
(C)1.414✓ Correct
(D)2.732

Answer: (C)

Solution

The angle of incidence with respect to the normal is

i = 4 5^{\circ}

.

The deviation is

D = i - r = 1 5^{\circ}

, so:

r = 4 5^{\circ} - 1 5^{\circ} = 3 0^{\circ}

Applying Snell's law:

n_{1} sin i = n_{2} sin r

1 \times sin 4 5^{\circ} = μ \times sin 3 0^{\circ}

\frac{1}{2} = μ \times \frac{1}{2}

μ = \frac{2}{2} = 2 \approx 1.414

The answer is (C) 1.414.

JEE Main · 2022 · 29 Jul 2022 · Shift 2 · Single correct option

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