Light wave enters from medium 1 to medium 2. Its velocity in 2^ nd medium is double from 1^ st . For total internal reflection the angle of incidence must be greater than

Step-by-step solution

Total internal reflection occurs when the angle of incidence is greater than critical angle (C) in the denser medium. ^1 ₂= Velocity of light in medium '1' Velocity of light in medium ' 2 ' ^1 ₂= v 2 v = 1 2 . Medium ' 1 ' is denser. or C= 1 2 = 30^ or C=30^ .