An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 687
electromagnetic signal
  نشال ِ برقامغناتی   
nešâl-e barqâmeqnâti

Fr.: signal électromagnétique   

Information transmitted by means of a modulated current or an electromagnetic wave and received by telephone, radio, television, etc.

electromagnetic; → signal.

electromagnetic spectrum
  بیناب ِ برقامغناتی   
binâb-e barqâmeqnâti

Fr.: spectre électromagnétique   

The range of frequencies over which electromagnetic waves are propagated. → electromagnetic radiation.

electromagnetic; → spectrum.

electromagnetic theory
  نگره‌ی ِ برقامغناتی   
negare-ye barqâmeqnâti

Fr.: théorie électromagnétique   

The description of combined electric and magnetic fields mainly by → Maxwell's equations. Same as → electromagnetism.

electromagnetic; → theory.

electromagnetic theory of light
  نگره‌ی ِ برقامغناتی ِ نور   
negare-ye barqâmeqnâti-ye nur

Fr.: théorie électromagnétique de la lumière   

The theory describing light as a wave phenomenon resulting from the combination of two electric and magnetic fields vibrating transversely and mutually at right angles. → electromagnetic radiation; → electromagnetic wave; → Maxwell's equations.

electromagnetic; → theory; → light.

electromagnetic wave
  موج ِ برقامغناتی   
mowj-e barqâmeqnâti

Fr.: onde électromagnétique   

A wave produced by oscillation or acceleration of an electric charge. → electromagnetic radiation.

electromagnetic; → wave.

  برقامغنات، برقامغناتیس   
barqâmeghnât, barqâmeghnâtis

Fr.: électromagnétisme   

1) The science dealing with the physical relations between → electricity and → magnetism. Same as → electromagnetic theory.
2) One of the four fundamental forces of nature, governing the electric and magnetic interaction between particles.

electro-; → magnetism.

electromotive force (EMF)
  نیروی ِ برقران   
niru-ye barqrân (#)

Fr.: force électromotrice   

The force, analogous to a pressure, which maintains a flow of electricity through a closed circuit. It is the algebraic sum of the → potential differences acting in the circuit. The unit of electromotive force is the → volt.

From → electro- + motive, from M.E., from M.Fr., from O.Fr. motif, from M.L. motivus "moving, impelling," from L. motus, p.p. of movere "to move," → motion; → force.

Niru, → force; barqrân, literally "driving electricity," from barq, → electro- + rân present stem of rândan, → drive.

elektron (#)

Fr.: électron   

The → elementary particle that possesses the smallest possible negative → electric charge. This structureless particle has an intrinsic → spin (1/2), a mass of 9.109 382 91 (40) x 10-31 kg, and an electric charge of 1.602 176 565(35) × 10-19 → coulombs, or 4.803 204 51(10) × 10-10 → esu.

Term first suggested in 1891 by Irish physicist G. J. Stoney (1826-1911); from electr-, from → electric + -on, a suffix used in the names of subatomic particles, probably extracted from → ion.

electron affinity
  کرونی ِ الکترونی   
karvani-ye elektroni

Fr.: affinité électronique   

The amount of energy released or absorbed in the process in which an electron is added to a neutral atom or molecule in gaseous state to form a negative ion.

electron; → affinity.

electron capture
  گیر‌افت ِ الکترون   
giroft-e elektron

Fr.: capture d'électron   

A process whereby an → unstable atom becomes stable. In this process, an → electron in an atom's inner shell is drawn into the → nucleus where it combines with a → proton, forming a → neutron and a → neutrino. The neutrino escapes from the atom's nucleus. The result is an element change, because the atom loses a proton. For example, an atom of → carbon (with 6 protons) becomes an atom of → boron (with 5 protons). Electron capture is also called K-capture since the captured electron usually comes from the atom's K-shell. See also → neutronization.

electron; → capture.

electron charge
  بار ِ الکترون   
bâr-e elektron (#)

Fr.: charge de l'électron   

The charge of one electron, e = -1.602 176 × 10-19coulombs or -4.803 204 51 × 10-10statcoulombs.

electron; → charge.

electron configuration
  همپیکرش ِ الکترونی   
hampeykareš-e elektroni

Fr.: configuration électronique   

Of an atom, a form of notation which shows how the electrons are distributed among the various atomic orbital and energy levels. The format consists of a series of numbers, letters and superscripts. For example, 1s2 2s2 2p3 means: 2 electrons in the 1s subshell, 2 electrons in the 2s subshell, and 3 electrons in the 2p subshell.

electron; → configuration.

electron degeneracy
  واگنی ِ الکترون   
vâgeni-ye elektron (#)

Fr.: dégénérescence des électrons   

A → degenerate matter in which electrons are very tightly packed together, as in a white dwarf, but cannot get closer than a certain limit to each other, because according to quantum mechanics laws (→ Pauli exclusion principle) the lowest energy levels can be occupied by only one electron. Therefore, electrons are forced into high energy states. And the significant pressure created by these high energy electrons supports white dwarf stars against their own gravity.

electron; → degeneracy.

electron density
  چگالی ِ الکترونی   
cagâli-ye elektroni (#)

Fr.: densité électronique   

The number of electrons per unit volume in an ionized medium, like an → H II region, as determined from → emission lines.

electron; → density.

electron diffraction
  پراش ِ الکترونی   
parâš-e elekroni (#)

Fr.: diffraction des électrons   

A diffraction phenomenon resulting from the passage of electrons through matter, analogous to the diffraction of visible light. This phenomenon is the main evidence for the existence of waves associated with elementary particles; → de Broglie wavelength.

electron; → diffraction.

electron mass
  جرم ِ الکترون   
jerm-e elekron (#)

Fr.: masse de l'électron   

The mass of an electron, which is 9.109 382 91 × 10-28 g.

electron; → mass.

electron radius
  شعاع ِ الکترون   
šo'â'-e elektron

Fr.: rayon de l'électron   

The classical size of the electron given by re = e2/mec2 = 2.81794 × 10-13 cm, where e and me are the → electron charge and → electron mass, respectively, and c is the → speed of light.

electron; → radius.

electron shell
  پوسته‌ی ِ الکترونی   
puste-ye elekroni (#)

Fr.: couche éléctronique   

Any of up to seven energy levels on which an electron may exist within an atom, the energies of the electrons on the same level being equal and on different levels being unequal. The number of electrons permitted in a shell is equal to 2n2. A shell contains n2 orbitals, and n subshells.

electron; → shell.

electron temperature
  دمای ِ الکترونی   
damâ-ye elektroni (#)

Fr.: température électronique   

1) The temperature of electrons in an interstellar ionized nebula (e.g. in → H II regions and → planetary nebulae) as determined by characteristic → emission lines (optical → forbidden lines or → radio recombination lines).
2) In the → solar wind, the temperature derived from the mean → thermal agitation of the electrons. More specifically, electric field receivers on board space probes carry out the spectroscopy of the → thermal noise due to the potential fluctuations produced by the thermal agitation of the electrons, yielding the electron temperature in certain conditions (N. Meyer-Vernet, 2007, Basics of the Solar Wind, Cambridge Univ. Press). See also → proton temperature.

electron; → temperature.

electron volt (eV)
elektron-volt (#)

Fr.: électron-volt   


electron; → volt.

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