Light is incident on an interface between water $(μ=4/3)$ and glass $(μ=3/2)$. For total internal reflection, light should be travelling from:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → glass to water and $∠i>∠i_c$
The critical angle $(θ_c)$ for total internal reflection,
$\sin θ_c=\frac{μ_2}{μ_1}$
when light is travelling from water to glass.
$\sin θ_c=\frac{3/2}{4/3}=\frac{9}{8}$ [$μ_2=\frac{3}{2}$ = water, $μ_1=\frac{4}{3}$ = Glass]
as,
$\sin θ_c$ cannot exceed 1, it is only possible when light travel from water to glass and $∠i>∠i_c$