The fundamental source of electromagnetic radiation is the vibrational interaction between an electric field and a magnetic field. This phenomena is driven by the motion of electrically induced particles propagating through a material or vacuum.
The Scottish physicist James Clerk Maxwell discovered that fluctuating electric and magnetic fields induce a type of radiation in the form of electromagnetic, or EM waves, which travel in a perpendicular direction to the fields. In a vacuum, an EM wave travels at the speed of light, which is approximately equal to 186,000 miles per second. These waves can propagate through space without a medium. EM waves possess momentum, manifest interference and diffraction and can acquire polarity. All EM waves are characterized by their wavelengths, amplitudes, frequencies, periods and velocities.
EM waves are quantized and contain a specific amount of energy that comes from light particles known as photons. These waves correspond to particular wavelengths and frequencies, used as the basis for classifying them into the electromagnetic spectrum. Common examples of EM waves include radio waves, X-rays, visible light, infrared rays, microwaves, ultraviolet radiation and gamma rays. Radio waves are emitted by radio and television stations, X-rays by X-ray machines used in the medical field, visible light by any object that can be seen by the naked eye, infrared by any heated material, microwaves by a microwave oven, ultraviolet by the sun and gamma rays by radioactive compounds.