Isaac Newton’s Prism Theory

saac Newton (1642 – 1726)

  • Isaac Newton was the first physicist to really understand the theories of rainbows.
  • Before Newton’s discoveries, theories made by Francesco Grimaldi and Rene Descartes claimed that light was made by waves.
  • Newton was adamant that light travelled as particles rather than waves.
  • He discovered this by refracting white light with a prism.
  • By doing so, he found that the light was resolved into its component colours: red, orange, yellow, green, blue and violet.
  • Previously, people had though that colour was a mixture of light and darkness and that prisms was actually a mixture of coloured light. Newton was the one who proved this theory to be false through his series of experiments.
  • Newton’s experiments involved setting up a prism near his window and projecting a 22 foot spectrum onto the far wall.
  • He then refracted the light back together and was able to prove through this that the prism itself did not have coloured light.

ewton refracting light through his prism.

newtons prism
Light reflected through two prisms show that colour is made from white light.

newtons prism1
Light can be divided into separate colours.

newtons prism3
very colour has a unique angle of refraction. This can be made using the right prism.

Newton’s theories were game changing for many artists. Newton conceptual arrangement of colours appeared around a circumference of a circle and this was fascinating for many artists as this allowed for the primary colours; reds, yellows and blues, to be arranged opposite their complementary colours; red opposite green. This denoted that each complementary would enhance the other’s effect through optical contrast.

ewton’s Colour Circle

In 1708, Claude Boutet designed a colour wheel based on Newton’s colour circle and was probably the first one to do so. Boutet was unable to represent the real spectral red that appears so he instead used a mixture of fire red and crimson and in the process omitted one of Newton’s two blue. This created some confusion, made worse by the fact that colourists would misread two of the labels orange and violet.

Boutet’s Colour Wheel


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