Concepts Of Physics MCQ Edition [Volume 1]PhysicsGeometrical Optics
Total internal reflection can occur only when
Options
- Alight travels from an optically rarer medium (lower refractive index) to an optically denser medium
- Blight travels from an optically denser medium to a rarer medium
- Cthe refractive indices of the two media are nearly equal
- Dthe refractive indices of the two media differ significantly
Correct answer
B. light travels from an optically denser medium to a rarer medium
Step-by-step solution
Total internal reflection occurs when a light ray travels from an optically denser medium to an optically rarer medium. According to Snell's law, ₁ i = ₂ r . For total internal reflection to occur, the angle of refraction r must reach 90^ for an angle of incidence i This implies i = ₂ ₁ 90^ = ₂ ₁ . Since i Thus, light must travel from a medium of higher refractive index (denser) to a medium of lower refractive index (rarer).