Critical angle for glass (n=1.5) to air: MCQ with Answer and Explanation

Critical angle for glass (n=1.5) to air:
A. 30°
B. 90°
C. 42°
D. 60°
Answer: Option C
Solution (By JKSSB Mock Tests)
sinθ_c = n₂/n₁ = 1/1.5 = 2/3 ⇒ θ_c = sin⁻¹(0.667) ≈ 42°. Total internal reflection condition. Memory tip: 'θ_c = sin⁻¹(1/n) for denser to air'. Optics calculation frequently tested in competitive exams with standard refractive indices.

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