Question:What is Refraction?
When a wave of any kind travels from one medium into another, the wave must change speed.
If the second medium is more dense then the wave must slow down.
If the second medium is less dense then the wave will speed up.
This changing of speed when a wave crosses the boundary from one material to another is called refraction.
Refraction is the change in speed of a wave when it travels across the interface from one material to another.