JEE Main202528 Jan 2025Morning ShiftPhysicsRay OpticsActual
A hemispherical vessel is completely filled with a liquid of refractive index . A small coin is kept at the lowest point ( O ) of the vessel as shown in figure. The minimum value of the refractive index of the liquid so that a person can see the coin from point E (at the level of the vessel) is
Options
- A3
- B3 2
- C3 2
- D2
Correct answer
D. 2
Step-by-step solution
For the rays from coin to reach the point E , the refracted rays must grazing the surface, i.e. they must be incident at critical angle _c inside the liquid. = 1 _c is minimum when _c is maximum. Maximum value of _c=45^ has a minimum value of 2 .