light

• Light travels


  1. From luminous objects

  2. To non luminous objects

  3. In a straight line

  4. Reflects back to the eyes
• Transparent


  Allows light through, you can see through (e.g. window glass)
• Translucent

  Allows some light through but it is scattered, makes object blurry to see through (e.g. tracing paper)
• Opaque

  Doesn't allow any light through, you can't see through (e.g. book)
• Incident ray


  The ray of light hitting the glass
• Angle of incidence


  The angle between the incident ray and the normal
• Refracted ray


  The light exiting the glass
• White light is made up of the 7 colours on the spectrum
• The 7 colours of the spectrum

  • red
  • orange
  • yellow
  • green
  • blue
  • indigo
  • violet
• red light travels faster in glass than blue light
• Light can be split using a prism
• A blue light shining through a red filter will give no light
• Black isn't a colour. Its absence of light.
• Dispersion


  The splitting up of white light inte its component colours
• All colours travel at the same speed in a vaccum (3x10 m/s)
• White isn't a colour but a mixture of all the colours of the rainbow.
• Filters absorb some colours of white light and lets other colours through to create coloured light
• a red filter absorbs all colours except red light
• a blue filter absorbs all colours apart from blue light
• a green filter absorbs all colours except a green light. it is used to separate out the green light from the red and blue light
• a magenta filter absorbs all colours apart from red and blue
• a cyan filter absorbs all colours except green and blur
• a yellow filter absorbs all colours except from red and green