Ray Optics

JEE Main level, single correct, medium

263 of 295

Question 263 of 295

A monochromatic light is incident at a certain angle on an equilateral triangular prism and suffers minimum deviation.

If the refractive index of the material of the prism is 3\sqrt{3},

then the angle of incidence is :

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Answer: (C) 60∘60^{\circ}

For minimum deviation:

r1=r2=A2=30∘\mathrm{r}_{1}=\mathrm{r}_{2}=\frac{\mathrm{A}}{2}=30^{\circ}

by Snell's law μ1sin⁡i=μ2sin⁡r\mu_{1} \sin \mathrm{i}=\mu_{2} \sin \mathrm{r}

1×sin⁡i=3×12=32⇒i=601 \times \sin i=\sqrt{3} \times \frac{1}{2}=\frac{\sqrt{3}}{2} \Rightarrow i=60

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