Colours in Physics

A series of free Science Lessons for 7th Grade and 8th Grade, KS3 and Checkpoint Science in preparation for GCSE and IGCSE Science.

Colours
Prism and Rainbow
White light is a mixture of many different colours, each with a different frequency. White light can be split up into a spectrum of these colours using a prism, a triangular block of glass or Perspex.

Light is refracted when it enters the prism, and each colour is refracted by a different amount. This means that the light leaving the prism is spread out into its different colours, a process called dispersion.

Here are the seven colours of the spectrum listed in order of their frequency, from the lowest frequency (fewest waves per second) to the highest frequency (most waves per second): red, orange, yellow, green, blue, indigo, violet

Coloured Lights
When different coloured lights are combined it is found that all the the colours can be made from different combinations of just three colours. They are red, green and blue and are called the primary colours of light.

Colours and paint
Paint contain tiny particles called pigments. The pigment absorbs some of the colours in sunlight and reflect others to give the paint its colour. Three colours of paint can be used to make almost all the other colours of paint. These colours are yellow, magenta and cyan. They are mixed together in different proportions to produce a wide range of colours.

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