A glass prism deviates the red and violet rays through 9° and 11° respectively. A second prism of equal angle deviates them through 11° and 13° respectively. The ratio of dispersive power of second prism to first prism is (a) 5: 6 (b) 6: 5 (c) 9: 13 (d) 13: 9

Answer: (a). ω = δv - δrδmean First prism: ω₁ = (11 - 9)/(10) = 2/10; second prism: ω₂ = (13 - 11)/(12) = 2/12 ω₂: ω₁ = 1/12: 1/10 = 10: 12 = 5: 6, so the answer is (a).

A glass prism deviates the red and violet rays through 9° and 11°… | MHT CET 2023 (12 May, Shift 2)

Q48MHT CET 2023 · 12 MAY · SHIFT 2Medium

Prism, Dispersion & Scattering

A glass prism deviates the red and violet rays through $9^\circ$ and $11^\circ$ respectively. A second prism of equal angle deviates them through $11^\circ$ and $13^\circ$ respectively. The ratio of dispersive power of second prism to first prism is

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Answer: (a)

$\omega = \dfrac{\delta_v - \delta_r}{\delta_{\text{mean}}}$
First prism: $\omega_1 = \frac{11 - 9}{10} = \frac{2}{10}$ ; second prism: $\omega_2 = \frac{13 - 11}{12} = \frac{2}{12}$
$\omega_2 : \omega_1 = \frac{1}{12} : \frac{1}{10} = 10 : 12 = 5 : 6$ , so the answer is (a).

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Prism, Dispersion & Scattering question from MHT CET 2023 (12 May, Shift 2)

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