Question

The angle of incidence is 40°, what is the value of the angle of refraction when the light travels from water to light flint glass?

Answer 1

The angle of refraction is

$$\theta_2=\arcsin(\sin\theta_1·\frac{n_1}{n_2}),\\\space\\ \theta_2=\arcsin(\sin40°·\frac{1.33}{1.66})=31°$$