|See also electromagnetic radiation a wave of energy propagated in an electromagnetic field|
A wave of energy consisting of electric and magnetic fields, oscillating at right angles to each other. See more at electromagnetic radiation.
Waves composed of undulating electrical fields and magnetic fields. The different kinds of electromagnetic waves, such as light and radio waves, form the electromagnetic spectrum. All electromagnetic waves have the same speed in a vacuum, a speed expressed by the letter c (the speed of light) and equal to about 186,000 miles (or 300,000 kilometers) per second.