Total Internal Reflection (TIR) is a fundamental optical phenomenon crucial for the operation of modern fiber optic communication systems. Which combination of conditions must be met for TIR to occur?

💡 Explanation:

Total Internal Reflection (TIR) is the complete reflection of a light ray at the boundary of two media. For TIR to occur, two strict conditions must be met: 1) The light must be traveling from an optically denser medium (higher refractive index, e.g., glass core of a fiber) to an optically rarer medium (lower refractive index, e.g., cladding). 2) The angle of incidence (the angle the ray makes with the normal) must exceed the critical angle (the specific angle of incidence for which the angle of refraction is 90 degrees).