Session 1, Page 7: Dispersion

When the rays of light pass from the air into a dense transparent medium, such as a prism, the different wavelengths of light travel at slightly different speeds and are therefore refracted by different amounts. Shorter wavelengths are diffracted more than longer wavelengths, causing the different colors present in white light to become spread out, as illustrated in Figure 8. This spreading is called dispersion.

With a basic understanding of the processes of refraction and dispersion, we can understand how a prism produces a spectrum.

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	$refraction5.gif (4295 bytes)$ Figure 10 Refraction and dispersion of light by a prism.