When light travels from one medium to another, it "bends" (refracts) in a predictable way which depends on the speed that light travels in each medium:
Snell's Law says that if a ray of light makes an angle ̸̸̸́̂̑1 (the angle of incidence) with the vertical in the first medium and an angle of ̸̸̸́̂̑2 (the angle of refraction) in the second medium, then
sin(̸̸̸́̂̑1) / sin(̸̸̸́̂̑2) = v1 / v2
where v1 is the speed of light in the first medium and v2 is the speed of light in the second medium.
When light passes from air to amber, v1/v2 = 1.55.
If the angle of incidence ̸̸̸́̂̑1 = 40°, what is the angle of refraction?
̸̸̸́̂̑2 = degrees