The visible spectrum
White
light can be split up using a prism to form a spectrum. In physcis,a
prism is a block of glass with a triangular cross-section. The light waves
are refracted as they enter and leave the prism. The shorter the wavelength
of the light, the more it is refracted. As a result, red light is refracted
the least and violet light is refracted the most, causing the coloured
light to spread out to form a spectrum.
The electromagnetic spectrum
Visible light is just one type of electromagnetic radiation. There are various types of electromagnetic radiation, with longer wavelengths of light than red light and with shorter wavelengths than violet light. All the different types of electromagnetic waves travel at the same speed through space.
[ This page has been adapted from www.bbc.co.uk/schools/gcsebitesize/science ]