radiation

(1) The process of emitting radiant energy in the form of electromagnetic waves or moving nuclear particles.

NOTE 1 Electromagnetic waves include x-rays, gamma rays, light, etc. These forms of radiation all consist of photons, which are quanta of electromagnetic energy.

NOTE 2 Nuclear particles include alpha particles (helium nuclei), beta particles (electrons), neutrons, and other atomic particles that can transfer energy to a material. Subatomic particles such as quarks are not considered.

(2) Energy radiated in the form of electromagnetic waves or moving nuclear particles.

NOTE See notes to "radiation" (1).

(3) The transmission of heat via electromagnetic waves.

References

Merriam-Webster's Collegiate Dict.
JESD89A, 10/06

JESD51-1, 12/95