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The critical angle for diamond (n ≈ 2.42) and water (n ≈ 1.33) is approximately:
ADiamond ≈ 24.4°, water ≈ 48.75°
BDiamond ≈ 48.75°, water ≈ 24.4°
CBoth ≈ 45°
DDiamond ≈ 90°, water ≈ 0°
Answer & Solution
Correct answer: A. Diamond ≈ 24.4°, water ≈ 48.75°
i_c = arcsin(1/n). **Diamond (n=2.42): i_c ≈ 24.4°** (small → most light TIRs → brilliant sparkle). **Water (n=1.33): i_c ≈ 48.75°**. **Crown glass (n=1.52): i_c ≈ 41.1°** — basis of 90°/180° reflecting prisms (i_c < 45°).
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