Unit 3 Properties of waves

Refraction of light

• Light rays can change direction when passing from one material into another because the rays move at different speeds in the two materials.
• Notice that the angle of incidence i and the angle of refraction r always lie between the light beam and the normal.
• A material in which light travels slowly is said to be optically dense.
• When travelling from an optically less dense material to a more dense material (such as air to glass), light bends towards the normal (diagram on the left above).
• When travelling from an optically more dense material to a less dense material (such as glass to air), light bends away from the normal (diagram on the right above).
• When light enters a different material:
  • the frequency stays the same
  • the wavelength changes
  • the speed changes.