Snell's Law│Please Help!

Question

A laser passing through air passes through an unknown liquid at an incident angle of 30 degrees. The laser is refracted such that the refracted angle is 20 degree relative to the normal line. What is the index of refraction of the unknown liquid?

Answer 1

As your title suggests, we can use Snell's Law here, which says that

sin(theta_1)/sin(theta_2) = n2/n1,

where theta_1 and theta_2 are the angles and n1 and n2 the refractive indices of the different media. In this case, we can n1 = the refractive index of air, and n2 be that of the unknown liquid. We're given the two angles, so we just have to solve

n2/n1 = sin(30)/sin(20), which becomes n2 = n1*sin(30)/sin(20).