Science 8: Unit C – Light and Optical Systems

Topic 3: Refraction

What is Refraction?• Refraction is the

bending of light rays as they enter a new medium (material)

Why Does it happen?• When light rays enter a thicker

medium from a thinner medium they slow down and bend TOWARDS the normal. (eg. from air to glass)

• When light rays enter a thinner medium from a thicker one they speed up and bend AWAY from the normal (eg. from glass back to air.

Law of Refraction• Law of Refraction: as the angle of

incidence increases, the angle of refraction increases, though not necessarily by the same amount.

• NOTE: refraction can also occur with the same material at two different temperatures.

How are reflection, refraction, and absorption different?• The angle of incidence does not

necessarily equal the angle of refraction.

• Reflection has to do with bouncing off a surface while refraction is bending of light rays.

• Absorption is the changing of light rays from light energy into another kind of energy (usually thermal energy).