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Another aspect of light that is quite common is the breaking up of white light into its constituent colours. For example, if a beam of white light enters a glass prism, as shown in the Figure below, what emerges from the other side is a spread out beam of many coloured light.
Figure 10.7: Dispersion of white light by a prism
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The explanation for this phenomenon is simple: the white light consists of literally all the colours in the rainbow. The various colours are refracted through different angles by the glass, and are ``dispersed'', or spread out. From the figure, we see that blue light gets bent more by the glass than red light. The triangular shape of the prism is designed to maximize this effect.