Refraction is the bending of light. Light bends whenever it travels from one transparent material to another. One example of this is light travelling through a glass.
The reason light bends when it passes between two materials is because it changes speed. If the new material is more dense ( for example air to glass ) the light slows down and bends towards the normal.
Light speeds up as it passes through a less dense material ( for example, glass to air ) and bends away from the normal.
Light Refraction Experiments
Reverse the direction of arrows with a glass of water.
You can also use refraction to make a coin disappear!
Find out how refraction plays a part in rainbows and how to bend light with a prism.