For a thin prism of small refracting angle A and refractive index n, the deviation δ is approximately
A{'text': 'δ = (n − 1) A', 'label': 'A'}
B{'text': 'δ = A / (n − 1)', 'label': 'B'}
C{'text': 'δ = A × n²', 'label': 'C'}
D{'text': 'δ = (n + 1) A', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': 'δ = (n − 1) A', 'label': 'A'}
1. For a thin prism, deviations at the two faces add; small-angle approximation gives sin θ ≈ θ.
2. The result is δ ≈ (n − 1) A.
3. This is the basis of dispersive power formulas.
_Source: NCERT Class 12 Physics Part II, Ch 9 §9.6_
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