Updated at 23 Jun 2026
The electromagnetic spectrum encompasses all electromagnetic phenomena, ordered by frequency and wavelength, ranging from radio waves and infrared to visible light and gamma rays. It includes both natural and artificial sources and is fundamental to understanding electromagnetic fields and radiation.
In the electromagnetic spectrum, all electromagnetic phenomena are classified according to frequency (number of oscillations per second; 1 hertz = 1 oscillation per second) or wavelength. In the “lower” range of the spectrum, frequency is almost always used as the unit of measurement, while in the “upper” range (optical radiation and “above”) wavelength is almost always used. Frequency and wavelength are in a defined ratio and can be converted into one another.
