electromagnetic radiation, radiation that is produced with a combination of magnetic and electric forces. It exists as a continuous spectrum of radiation, from that with the highest energy level and shortest wavelength (gamma rays) to that with the lowest energy and longest wavelength (long radio waves). The visible part of the electromagnetic spectrum has a wavelength between 400 and 700 nm. Ultraviolet and infrared radiation have wavelengths just below the short end and above the long end of the visible spectrum, respectively. X-rays have wavelengths from about 0.005 to 10 nm. All forms of electromagnetic radiation travel at the speed of light.
