The angle of refraction is 15.6 deg.
When a ray of light passes from medium 1 to medium 2, the refractive index of medium 2 with respect to 1 is the ratio of the absolute refractive index of medium 2 and medium 1
[tex] _1n_2 =\frac{n_2}{n_1} [/tex]
When light passes from air into diamond, with the given values of refractive indices,
[tex] _an_d =\frac{n_d}{n_a} =\frac{2.42}{1.0003} =2.4193 [/tex]
According to Snell's law,
[tex] _an_d=\frac{sini}{sinr} \\
sinr=\frac{sini}{_an_d} =\frac{sin(40.5)}{2.4193}=0.2684\\
r=arcsin(0.2684)=15.57 deg [/tex]
The angle of refraction is 15.6 deg
