Question

Does the critical angle for total internal reflection is greater when a ray of light travels from glass to water than when it travels from glass to air.

Answer 1

Let the critical angle be $C_1$ when ray travels from glass to water.

$sin{C}_1=\frac{{\mu }_{water}}{{\mu }_{glass}}$

Let the critical angle be $C_2$ when ray travels from glass to air.

$sin{C}_2=\frac{{\mu }_{air}}{{\mu }_{glass}}$

As we know ${\mu }_{water}>{\mu }_{air}$

Hence $sin{C}_1>sin{C}_2$

So $C_1>C_2$