MHT CET202617 April 2026Evening ShiftPhysicsRay OpticsActual
A ray of light incident on one face of an equilateral glass prism having refractive index 2 , produces the emergent ray which just grazes along the adjacent face. The value of angle of incidence is ( 90^ = 1) ( 30^ = 1 2 ) ( 45^ = 1 2 )
Options
- A⁻¹ ( 2 15^ )
- B⁻¹ ( 1 2 15^ )
- C⁻¹ ( 2 30^ )
- D⁻¹ ( 1 2 45^ )
Correct answer
A. ⁻¹ ( 2 15^ )
Step-by-step solution
For an equilateral prism, the angle of the prism is A = 60^ . The emergent ray grazes the adjacent face, so the angle of emergence is e = 90^ . Applying Snell's law at the second face: r₂ = 1 e 2 r₂ = 90^ = 1 r₂ = 1 2 r₂ = 45^ Using the relation for the angle of the prism A = r₁ + r₂ : r₁ + 45^ = 60^ r₁ = 15^ Applying Snell's law at the first face: 1 i = r₁ i = 2 15^ i = ⁻¹ ( 2 15^ ) Answer: ⁻¹ ( 2 15^ )