Refraction is the change of direction by a wave due to a change in medium, and thus a change in speed.

The most common example of this is with light, although it can happen with any type of wave. This happens when it travels from one medium to another medium, with different refractive indexes.

Penny Test[edit | edit source]

You can see the effect of refraction with a easy experiment.

Place a penny in an opaque container so that the penny is not visible at that point, but you can see the top. Keeping your head in the same point, slowly fill the container up with water, and soon you should be able to see the coin.

Important formulae[edit | edit source]

The important refraction formulae include:

speed of light in a vacuum / speed of light in the material = n

Bearing in mind that n (refractive index) has no units and the speed of light in a vacuum (c) is 3.0 x 10^8.

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