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For a prism, the angle of deviation D is related to the angle of prism A and refractive index n by (at minimum deviation):
An = (D + A)/A
Bn = sin((A + D_m)/2) / sin(A/2) — the prism formula
Cn = D × A
Dn = cos(A) × sin(D)
Answer & Solution
Correct answer: B. n = sin((A + D_m)/2) / sin(A/2) — the prism formula
**Prism formula at minimum deviation**: n = sin((A + D_m)/2) / sin(A/2). Used to determine refractive index of the prism material experimentally. At minimum deviation, the ray passes symmetrically through the prism (i₁ = i₂; the refracted ray inside is parallel to the base).
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