JEE Main202431 Jan 2024Morning ShiftPhysicsRay OpticsActual
The refractive index of a prism with apex angle A is c o t A 2 . The angle of minimum deviation is :
Options
- Aδ m = 180 ° - A
- Bδ m = 180 ° - 3 A
- Cδ m = 180 ° - 4 A
- Dδ m = 180 ° - 2 A
Correct answer
D. δ m = 180 ° - 2 A
Step-by-step solution
As we know, μ = sin A + δ m 2 sin A 2 ⇒ cos A 2 sin A 2 = sin A + δ m 2 sin A 2 ⇒ sin π 2 - A 2 = sin A + δ m 2 ⇒ π 2 - A 2 = A 2 + δ m 2 ⇒ δ m = π - 2 A = 180 ° - 2 A