electromagnetic radiation (redirected from Theory of radiation)

electromagnetic radiation

n

(Physics / General Physics) radiation consisting of self-sustaining oscillating electric and magnetic fields at right angles to each other and to the direction of propagation. It does not require a supporting medium and travels through empty space at the speed of light See also photon

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electromagnetic radiation

Energy in the form of transverse magnetic and electric waves. In a vacuum, these waves travel at the speed of light (which is itself a form of electromagnetic radiation). The acceleration of electric charges (such as alternating current in a radio transmitter) gives rise to electromagnetic radiation. Other common examples of electromagnetic radiation are x-rays, microwaves, and radio waves. A single unit, or quantum, of electromagnetic radiation is called a photon. See also electromagnetismpolarization

A Closer Look In the nineteenth century, physicists discovered that a changing electric field creates a magnetic field and vice versa. Thus a variation in an electric field (for example, the changing field created when a charged particle such as an electron moves up and down) will generate a magnetic field, which in turn induces an electric field. Equations formulated by James Clerk Maxwell predicted that these fields could potentially reinforce each other, creating an electromagnetic ripple that propagates through space. In fact, visible light and all other forms of electromagnetic radiation consist exactly of such waves of mutually reinforcing electric and magnetic fields, traveling at the speed of light. The frequency of the radiation determines how it interacts with charged particles, especially with the electrons of atoms, which absorb and reemit the radiation. The energy of the electromagnetic radiation is proportional to its frequency: the greater the frequency of the waves, the greater their energy. Electromagnetic radiation can also be conceived of as streams of particles known as photons. The photon is the quantum (the smallest possible unit) of electromagnetic radiation. In quantum mechanics, all phenomena in which charged particles interact with one another, as in the binding of protons and electrons in an atom or the formation of chemical bonds between atoms in a molecule, can be understood as an exchange of photons by the charged particles.

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Radiation made up of oscillating electric and magnetic fields and propagated with the speed of light. Includes gamma radiation, X-rays, ultraviolet, visible, and infrared radiation, and radar and radio waves.

Thesaurus

Noun

1.

electromagnetic radiation - radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge electromagnetic wave, nonparticulate radiation photon - a quantum of electromagnetic radiation; an elementary particle that is its own antiparticle actinic radiation, actinic ray - electromagnetic radiation that can produce photochemical reactions electron beam, beam, ray - a group of nearly parallel lines of electromagnetic radiation black-body radiation, blackbody radiation - the electromagnetic radiation that would be radiated from an ideal black body; the distribution of energy in the radiated spectrum of a black body depends only on temperature and is determined by Planck's radiation law Hertzian wave - an electromagnetic wave generated by oscillations in an electric circuit gamma radiation, gamma ray - electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength line - a single frequency (or very narrow band) of radiation in a spectrum microwave - a short electromagnetic wave (longer than infrared but shorter than radio waves); used for radar and microwave ovens and for transmitting telephone, facsimile, video and data radiation - energy that is radiated or transmitted in the form of rays or waves or particles radio emission, radio radiation, radio wave - an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m roentgen ray, X ray, X-radiation, X-ray - electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target