Question

Does refraction change the direction of light when it passes from air to glass?

Answer 1

As long as the light strikes the glass with an angle of incidence greater than `0^o`, then yes, the direction will change. This occurs anytime you have 2 materials with different indices of refraction.

As light passes from air (with a low index of refraction) to glass (with a higher index of refraction), it will slow down, which bends the light toward the normal.

If the light passes from glass to air, it will speed up, which bends the light away from the normal.

The angle of refraction can be calculated using Snell's Law (`n_1 sin Theta_1 = n_2 sin Theta_2`), where `Theta_1` is the angle of incidence and you know the two indices of refraction.