The second law of refraction is also known as:

The second law of refraction is also known as snell's law. According to this law, "the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant'. It is given as,
$\frac{\mathrm{Sin} \mathrm{i} }{\mathrm{Sin} \mathrm{r} } = \mathrm{Constant}$