Total Internal Reflection question from MHT CET 2024 (3 May, Shift 2)

Answer: (b)

1. $\sin C = \frac{1}{\mu}$, and $\mu$ increases from red to violet, so $C$ decreases from red to violet.
2. The angle of incidence equals $C$ for green (green just grazes).
3. Violet, indigo and blue have $C$ smaller than this angle, so they are totally reflected back into the glass.
4. Yellow, orange and red have larger $C$, so they come out into the air.
5. So the answer is (b) violet, indigo, blue.