electromagnetic wave. wave that involves perpendicular oscillations in the electric and magnetic fields, moving at a speed of 2.99792458×108 m/s in a vacuum away from the source. gamma rays, x-rays, ultraviolet light, visible light, infrared radiation, and radio waves are all electromagnetic waves.
Radiation which has both electric and magnetic properties. Examples: microwaves, light, infra-red, ultraviolet, X rays, gamma, radio and television. Travels at 300 million m/s.
Energy that travels through space in the form of waves. The highest frequencies are gamma-rays; the lowest frequencies are radio waves. (Microwaves are a type of radio wave.) All electromagnetic radiation travels at light speed – 300,000 kilometres per second in a vacuum. Shorter wavelength radiation (eg, ultraviolet) carries more energy and is likely to be more harmful to living tissue. For more information see Electromagnetic Spectrum (NASA's Observatorium, USA).