Lesson 5 of 7

Colour and prisms

Goal: Explain how a prism splits white light.

Puzzles for this lesson

Word search0 of 8 foundCrossword0 of 34 letters
A rainbow over green hills, with red on the outside of the bow and violet on the inside

White light is a mixture of colours. A prism splits it into a spectrum.

  • The spectrum runs from red to violet. We name seven colours in it, always in the same order: red, orange, yellow, green, blue, indigo, violet.
  • A prism refracts each colour by a different amount. Red bends the least and violet the most, so the colours spread out. This is called dispersion.
  • Each colour of light has its own frequency. Of the colours we can see, red has the lowest frequency and violet the highest.
  • A rainbow forms when drops of rain split sunlight into its colours.

Your turn

This lesson’s activity starts here in a moment.

Check yourself

Knowledge organiser

This lesson on one page. Tap it to make it bigger.

Key words in this lesson

Spectrum The band of colours made when white light is split up

Dispersion The splitting of white light into its colours

For teachers: AQA 3.4.2 · Cambridge 8Ps.03