In an experiment for determination of refractive index of glass of a prism by i - δ plot, it was found that a ray incident at angle 35°, suffers a deviation of 40° and that it emerges at angle 79° In that case which of the following is closest to the maximum possible value of the refractive index? (a) 1.7 (b) 1.8 (c) 1.5 (d) 1.6

Answer: (c). δ = i + e - A ⇒ A = 35° + 79° - 40° = 74° Minimum deviation cannot exceed any measured deviation, so δm ≤ 40°. μmax = (sin (74°+40°)/(2))/(sin 37°) = (sin 57°)/(sin 37°) = (0.839)/(0.602) ≈ 1.39 The closest option is (c) 1.5.

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Prism, Dispersion & Scattering

In an experiment for determination of refractive index of glass of a prism by $i - \delta$ plot, it was found that a ray incident at angle $35^\circ$ , suffers a deviation of $40^\circ$ and that it emerges at angle $79^\circ$ In that case which of the following is closest to the maximum possible value of the refractive index?

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Answer: (c)

$\delta = i + e - A \Rightarrow A = 35^\circ + 79^\circ - 40^\circ = 74^\circ$
Minimum deviation cannot exceed any measured deviation, so $\delta_m \le 40^\circ$ .
$\mu_{\max} = \dfrac{\sin\frac{74^\circ+40^\circ}{2}}{\sin 37^\circ} = \dfrac{\sin 57^\circ}{\sin 37^\circ} = \dfrac{0.839}{0.602} \approx 1.39$
The closest option is (c) $1.5$ .

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