Total Internal Reflection Laws

Steps:

• Define total internal reflection (TIR): occurs when light travels from denser to rarer medium at angle of incidence greater than critical angle.
• Recall critical angle formula: $c = \sin^{-1}(1/n)$, where $n$ is refractive index of denser medium.
• Apply reflection law: in TIR, incident ray reflects entirely, so angle of incidence equals angle of reflection.
• Evaluate each option against these principles to identify the correct statement.

Why C is correct:

• Laws of reflection state that for any reflection, including TIR, the angle of incidence equals the angle of reflection.

Why the others are wrong:

• A: TIR requires light from denser (e.g., glass) to rarer (e.g., air) medium, not air to glass.
• B: Larger refractive index $n$ makes critical angle smaller, as $\sin c = 1/n$.
• D: TIR occurs only when angle of incidence exceeds critical angle, not less than it.

Final answer: C