electromagnetic wave

An electromagnetic wave is an electric field and associated magnetic field spreading in wavelike-fashion through space at a speed of about 300,000 kilometers per second, with its direction and intensity at any point in space oscillating rapidly back and forth. James Clerk's Maxwell's theory in 1864 suggested that light was such a wave, and today we know that such waves include all forms of light – also infrared and ultraviolet, as well as radio waves, microwaves, X-rays and gamma rays.


See also electromagnetic radiation and electromagnetic spectrum.