Q 12-09-012NEETNEET 2021Top questionMedium
Find the value of the angle of emergence from the prism. Refractive index of the glass is $\sqrt{3}$.
Answer: (B) $60°$
The ray strikes the slanting face normally, so it enters without bending.
The slanting face makes $60°$ with the base, so the ray inside (perpendicular to that face) travels at $30°$ below the horizontal. It meets the vertical face at an angle of incidence of $30°$ (measured from the horizontal normal).
This is less than the critical angle ($\sin C = 1/\sqrt{3}$, $C \approx 35°$), so the ray emerges. Snell's law at the vertical face:
$$\sqrt{3}\sin 30° = \sin e \;\Rightarrow\; \sin e = \frac{\sqrt{3}}{2} \;\Rightarrow\; e = 60°$$
Solution by Sreeraj P, M.Sc Physics