Explanation

The critical angle is the angle of incidence above which total internal reflection occurs.

It can be calculated using Snell's law:

n1 sin(θ1) = n2 sin(θ2)

where n1 = 1.33 (refractive index of water), θ1 = critical angle, n2 = 1 (refractive index of air), and θ2 = 90° (angle of refraction).

Rearranging the equation to solve for θ1, we get:

θ1 = arcsin(n2 / n1)

Substituting the values, we get:

θ1 = arcsin(1 / 1.33) ≈ 48.8°

So, the critical angle is approximately 48.8°.