A thin prism of refracting angle 5° is made of glass with n = 1.5. The deviation δ of a light ray passing through it is approximately
A{'text': '7.5°', 'label': 'A'}
B{'text': '2.5°', 'label': 'B'}
C{'text': '5.0°', 'label': 'C'}
D{'text': '1.25°', 'label': 'D'}
Answer & Solution
Correct answer: B. {'text': '2.5°', 'label': 'B'}
1. δ = (n − 1) A for a small-angle prism.
2. δ = (1.5 − 1) × 5° = 0.5 × 5° = 2.5°.
3. (A) uses A/4; (C) ignores the (n − 1) factor; (D) doubles incorrectly.
_Source: NCERT Class 12 Physics Part II, Ch 9 §9.6_
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