A thin prism of angle 15° made of glass of refractive index μ 1 = 1.5 is combined with another prism of glass of refractive index μ 2 = 1.75. The combination of the prisms produces dispersion without deviation. The angle of the second prism should be (a) 5° (b) 7° (c) 10° (d) 12°

Answer: (c). No deviation: (μ₁ - 1)A₁ = (μ₂ - 1)A₂. 0.5 × 15° = 0.75 × A₂ A₂ = 10° So the answer is (c) 10°.

A thin prism of angle 15° made of glass of refractive index μ 1 = 1.5… | NEET 2011 (AIPMT, Mains)

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Prism, Dispersion & Scattering

A thin prism of angle 15° made of glass of refractive index $\mu$ 1 = 1.5 is combined with another prism of glass of refractive index $\mu$ 2 = 1.75. The combination of the prisms produces dispersion without deviation. The angle of the second prism should be

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Answer: (c)

No deviation: $(\mu_1 - 1)A_1 = (\mu_2 - 1)A_2$ .
$0.5 \times 15^\circ = 0.75 \times A_2$
$A_2 = 10^\circ$
So the answer is (c) $10^\circ$ .

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