Question

What is the critical angle for light traveling from diamond into water?

Answer 1

By definition, the critical angle is:

$$\theta_c = \arcsin\left(\dfrac{n_2}{n_1} \right)$$

where $n_1 = 2.417$ is the refractive index of diamond, and $n_2 = 1.333$ is the refractive index of water. Thus, obtain:

$$\theta_c = \arcsin\left(\dfrac{1.333}{2.417} \right) \approx 33.5\degree$$

Answer. $33.5\degree$.