Refraction is a common everyday phenomenon that helps answer the following questions: Why does a straw in a glass of water look bent? Why do people look shorter in swimming pools? Why do mirages happen? The fact that light “bends” when moving from one medium to another helps answer all of these questions. This bending fundamentally results from a difference in the speed that light travels within different substances, which you can quantify using the index of refraction.
The Index of Refraction tells you something about how much a light ray will bend when crossing the boundary from one medium to another. It can be quantified as the speed of light in vacuum \(c\) divided by the speed of light in a given medium \(v\text{:}\)
Draw a ray diagram for light that travels from air (\(n = 1.00\)) into oil (\(n = 1.45\)) and then into water (\(n = 1.33\)). Which way does the light bend at each change of medium?
