Did you know? The primary colours of light are different to the primary colours of paint/ink! We are used to knowing that the primary colours of paint are red, blue and yellow, or (if you want to be technical) magenta, cyan and yellow. But the primary colours of light are actually red, green and blue. Have a go and mixing the light and colour in this experiment.

You will need:

• Colour filters (coloured plastic wallets work well) – make sure to have red, green and blue!
• 2 torches
• A white surface e.g. wall or paper

Method:

• Shine the torch through a colour filter so the light projects onto the white surface.
• Get the second torch and put a different filter over the end.
• Project the 2 colours on top of each other – what happens?
• Try mixing the colours, do they make the colours you expected them to?
• What happens if you mix 3 colours? – Hold 2 filters on one torch and one on the other!
• Try mixing the primary colours to see if they make white.

The science bit:

Primary colours are the colours that can be mixed to make secondary colours. The reason the primary colours of ink are different to the primary colours of light is really interesting. If you mix together all 3 primary colours of ink (magenta, cyan and yellow) you will get black. The reason we usually think they make brown is because we often mix red, blue and yellow which are slightly different. If you mix together the primary colours of light (red, green and blue) you will get white – which is what we normally see from lightbulbs etc. All the other colours we see in a rainbow are made from red, green and blue, which is why we call light a spectrum. Light and colour go hand in hand!