Answer:
33 degrees
Explanation:
The critical angle for a light ray moving from a denser medium with refractive index [tex]n_1[/tex] to a second medium with refractive index [tex]n_2[/tex] is given by
[tex]\theta_c = sin^{-1} (\frac{n_2}{n_1})[/tex]
In this case, the critical angle occurs when light moves from diamond to water. The index of refraction of the two materials are:
[tex]n_d = 2.42[/tex] for diamond
[tex]n_w = 1.33[/tex] for water
So the critical angle is
[tex]\theta_c = sin^{-1} (\frac{1.33}{2.42})=sin^{-1}(0.550)=33.3^{\circ}[/tex]