What is the critical angle of light traveling from diamond into water? Diamond has a refractive index of 2.4, and water has a refractive index of 1.3.

We will use the formula θ_{c}
= sin^{-1} (n_{2}/n_{1}) _{. }We plug in all of
the values we know,

and get θ_{c} = sin^{-1}1.3/2.4
= 33°.