1. tan⁻¹(0.750) 2. sin⁻¹(0.500) 3. sin⁻¹(0.750) 4. tan⁻¹(0.500)

Two transparent media A and B are separated by a plane boundary. The speed of light in those media are 1.5 × 10^8 m/s and 2.0 × 10^8 m/s, respectively. The critical angle for a ray of light for these two media is :

1. \(\tan^{-1}(0.750)\)

2. \(\sin^{-1}(0.500)\)

3. \(\sin^{-1}(0.750)\)

4. \(\tan^{-1}(0.500)\)

Doubtly Asked 30 Oct 2026 NEET UG 2022 Practice test neet Save WhatsApp Report

Best answer

Answer: 3. \(\sin^{-1}(0.750)\)

Refractive index \(n=c/v\): \(n_A=\dfrac{3\times10^8}{1.5\times10^8}=2\) and \(n_B=\dfrac{3\times10^8}{2\times10^8}=1.5\).

Total internal reflection is possible when light goes from the denser medium A to the rarer B, and \(\sin C=\dfrac{n_B}{n_A}=\dfrac{1.5}{2}=0.75\).

\(C=\sin^{-1}(0.750)\). Option (3).

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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