JEE Main · 2024 · 08 Apr 2024 · Shift 1 · Geometrical Optics

Critical angle of incidence for a pair of optical media is

4 5^{\circ}

. The refractive indices of first and second media are in the ratio:

(A) $2 : 1$ ✓ Correct
(B) $1 : 2$
(C) $1 : 2$
(D) $2 : 1$

Answer: (A)

Solution

Total internal reflection from denser (

μ_{1}

) to rarer (

μ_{2}

sin θ_{c} = \frac{μ _{2}}{μ _{1}}

. With

θ_{c} = 4 5^{\circ}

\frac{μ _{2}}{μ _{1}} = \frac{1}{2}

, so

μ_{1} : μ_{2} = 2 : 1

. Option (A).

JEE Main · 2024 · 08 Apr 2024 · Shift 1 · Single correct option

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