Filters

• Colour filters


  Transparent objects that absorb most wavelengths of light and just let some through
• Eg. red cellophane


  • Everything viewed though it appears to be either a shade of red or black
• Colour Filters


  • Only Let Through Particular Wavelengths
• Colour filters


  1. Filter out different wavelengths of light

  2. Only certain colours (wavelengths) are transmitted

  3. The rest are absorbed
• Primary colour filter


  Only transmits that colour
• If white light is shone at a blue colour filter

  • Only blue light will be let through
  • The rest of the light will be absorbed
• If you look at a blue object through a blue colour filter

  It would still look blue
• If the object was e.g. red (or any colour not made from blue light)

  The object would appear black when viewed through a blue filter
• Filters that aren't for primary colours

  Let through both the wavelengths of light for that colour AND the wavelengths of the primary colours that can be added together to make that colour