KVPY2016PhysicsRay Optics
A rectangular block is composed of three different glass prisms (with refractive indices ₁, ₂ and ₃ ) as shown in the figure below. A ray of light incident normal to the left face emerges normal to the right face. Then the refractive indices are related by
Options
- A₁²+ ₂²=2 ₃²
- B₁²+ ₂²= ₃²
- C₁²+ ₃²=2 ₂²
- D₂²+ ₃²=2 ₁²
Correct answer
C. ₁²+ ₃²=2 ₂²
Step-by-step solution
for surface AB : ₁ 45^ = ₂ ₁ (1) for surface AC : ₂ ( - ₁ )= ₃ 45 ₃ 45^ = ₂ ₁ (2) =90^ Squaring and adding equation (1) & (2) ₁² 2 + ₃² 2 = ₂² ₁²+ ₃²=2 ₂²