Unit 6

• Key Words


  • dispersion
  • spectrum
  • primary
  • secondary
• Breaking up white light is called dispersion
• The prism disperses the light
• Colours in white light

  • Red
  • Orange
  • Yellow
  • Green
  • Blue
  • Indigo
  • Violet
• Red


  Is refracted the least
• Violet


  Is refracted the most
• The shape of the prism means colours spread out even more on leaving the prism
• A small spectrum can be seen with a rectangular glass block but the colours do not spread out as much
• The 7 colours are always in the same order when white light is broken up
• Raindrops split sunlight


  Rainbows are formed
• Raindrops behave like small prisms
• The order of colours in a rainbow is the same as in the spectrum
• ROY GBIV is a mnemonic to remember the order of colours
• When a second prism is added upside down, white light is formed again
• The image stays on the retina for about 1/10 of a second
• When the disc spins very fast, all the colours of the rainbow appear on the retina together
• The colours combine to form white light