1. The Index of Refraction
The speed of light changes as it goes from one medium to another
Light travels fastest in a vacuum – 3x108m/s
The ratio between the speed of light in a vacuum (c = 3x108m/s ) and the speed of light in a medium is called the index of refraction
The higher the index of refraction, the higher the optical density of the medium, the slower the speed of light and the more light bends
air (n=1.00), glass (n=1.52), diamond (n=2.42)
12.4 #2-9

2. Rules for Refraction Snell’s Law n1 (sin 1) = n2 (sin 2)
The incident ray, refracted ray and the normal all lie in the same plane
The incident ray and refracted ray are always on opposite sides of the normal
Light bends towards the normal when the going into a more dense material
Light bends away from the normal when going into a less dense material n1 n2 R i
Snell’s Law n1 (sin 1) = n2 (sin 2)
n1(sin  i) = n2 (sin  R)

3. Example of Refraction