RADIATION

Transfer of heat by electromagnetic waves.

Any heated surface loses heat to cooler surrounding space or surfaces through radiation. The earth receives its heat from the sun by radiation. The heat rays are turned into heat as they strike an object which will absorb some or all of the heat transmitted.

An emission, of varying content, from a disturbed atom undergoing internal change. There are two broad classifications: (A) Corpuscular, comprising streams of particles, either neutral or charged, e.g. protons, neutrons, electrons; and (B) Electromagnetic, comprising wave-like emissions as gamma, ultraviolet, etc.