Senior ELP Science finding out how to make pictures using only 3 colours of light…

Have you ever wondered how your television screen shows such wonderful pictures? Did you realise that these pictures are made using only three colours of light in the first place?


Here is a close up of a television screen. You can clearly see the three colours it uses to generate other colours – and therefore pictures. The 3 main colours are

  • red
  • blue
  • green

By mixing red and green you can make yellow light. By mixing red and blue you can make magenta light (pinky colour). By mixing blue and green you can make cyan (turquoisy colour). By mixing red, green and blue light all together at the same time you can make white light!

This is the basis for making coloured pictures on the television screen.

The process for making colour described above is known as additive colour mixing. Additive mixing happens when coloured light is superimposed to make new colours. This can happen by projecting different coloured lights on top of one another, by flashing the lights so quickly we can’t see the individual colours, or by making adjacent patches of the colours so small that they blur together in our eyes. It is this last technique (small dots of light) that is most often used in colour televisions. There are other important parts of making colour television work. These include breaking the picture up into small spots of light, called pixels.

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