Isaac Newton discovered in 1672 that light could be split into many colours by a prism, and used this idea to analyse light. The colours produced by light passing through a prism are arranged in a precise spectrum from red through orange, yellow, green, blue, indigo and violet.  The order of colours is always the same, and each colour has a unique signature identifying its location in the spectrum. The signature of colour is the wavelength of light.

 

Miriana, Shania and Gabriella have set up this video to explain the spectrum of light and how a prism is used to show the colours of white light.