Refraction

• When a wave crosses a boundary between materials at an angle, it changes direction
• The refraction amount depends on how much the wave speeds up or slows down, this depends on the density of the two materials
• If it slows down, it will bend towards the normal
• If it speeds up, it will bend away from the normal
• The wavelength of a wave changed when it is refracted but the frequency stays the same
• If the wave is travelling along the normal, it will change speed but it is not refracted
• The optical density is a measure of how quickly light can travel through it, the higher the density the slower an object travels through it
• Light always bends towards the normal if it is passing into a material with a greater optical density (slower)