Q. 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
Solution:
Total internal reflection occurs when theangle of incidence is greater than critical angle (C) in the denser medium.
$^{1}\mu_{2}=\frac{Velocity of light in medium ’1’}{Velocity of light in medium ’2’}$
$^{1}\mu_{2}=\frac{v}{2v}=\frac{1}{2}.$ Medium ‘1’ is denser.
or $\quad$ sin $C=\frac{1}{2}$ = sin30$^{\circ}$ or C = 30$^{\circ}.$
