Seeing Colour
Science: KS3, topic 3.3.27
Seeing Colour
When we see different colours, we are just looking at different frequencies of light that reflect into our eyes.
Primary and secondary colours
- The three primary colours of light are: green, red and blue.
- If we mix these colours, we get our secondary colours:
- Red + green → yellow.
- Green + blue → cyan.
- Blue + red → magenta.
- Red + green + blue → white.
- White light contains all the colours.
Seeing colours
- We see objects as having a colour because that colour reflects off the object and the other colours are absorbed.
- So a red apple is red because the apple reflects red light and absorbs all other colours.
- White paper reflects all the colours and black paper absorbs all the colours.
Colour filters
- A coloured filter will only transmit that colour of light.
- So a blue filter will only transmit blue light and absorb all other colours.
- If you hold a blue filter and a red filter up, the blue light that is transmitted will be absorbed by the red filter.
Test yourself on Seeing Colour
What colour of light is let through by a red filter?
Which mixtures of primary colours yields the right secondary colours?
What colours are absorbed by a red apple?