Question

A beam of light in air strikes a plate of crown glass at an angle of incidence of 40°. What is the angle of refraction?

Answer 1

$n_1\sin40°=n_2\sin\beta\to$

$\beta=\sin^{-1}(n_1\sin40°/n_2)=\sin^{-1}(1\cdot\sin40°/1.52)\approx25°$