Figure 3-7The Electromagnetic Spectrum The full array of all types of electromagnetic radiation is called the electromagnetic spectrum. It extends from the longest-wavelength radio waves to the shortest-wavelength gamma rays. Visible light forms only a tiny portion of the full electromagnetic spectrum. Note that 1 μm (micrometer) is 10^-6 m, and 1 nm (nanometer) is 10^-9 m. The insets show how we are now using all parts of the electromagnetic spectrum here on Earth.