For normal dispersion, μVμR. A white ray inside glass is incident on a glass-air surface while the incidence angle is gradually increased. Which colour starts undergoing TIR first?

Question

For normal dispersion, μV>μR. A white ray inside glass is incident on a glass-air surface while the incidence angle is gradually increased. Which colour starts undergoing TIR first?

G1 Physics · Accepted Answer

C=sin⁻¹(1/μ). Larger μ gives smaller critical angle. Therefore violet reaches the TIR condition first.