Key learning points

1. All colours of light can be created by mixing the primary colours of light; red, green and blue.
2. Mixing equal amounts of two primary colours creates a secondary colour. All three mixed in equal amounts makes white.
3. The retina, on the back of the eye, detects light. When there is no light, we see black.
4. On the retina, three types of cone cell detect either red, green or blue light, and rod cells detect brightness.
5. Display screens are made of tiny red, green and blue lights (pixels) which vary in brightness to make different colours.

Keywords

• Primary colour - The colours of light from which all other colours of light can be made (red, green and blue).

• Secondary colour - Colours of light that are made by mixing two primary colours in equal amounts.

• Retina - The back surface of the eye that detects light.

• Cone cell - The cells at the back of the eye that detect colour.

• Rod cell - The cells at the back of the eye that detect brightness.

Common misconception