Electromagnetic spectrum. Computer illustration showing the electromagnetic (EM) spectrum (across centre) and the component colours of visible light (across bottom). The changing wavelength of EM radiation through the spectrum is shown by the trace across top. At the high wavelength end of the spectrum are (from left to right): gamma rays, X-rays and ultraviolet (UV) light. In the centre of the EM spectrum are wavelengths that the human eye can see, known as visible light. Visible light comprises light of different wavelengths and energies, and hence colours. At the low wavelength end of the EM spectrum (centre to right) are: infrared (IR) radiation, microwaves and radio waves.