An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 13048 Search : far
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.

electromagnetism
  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.

electron
  الکترون   
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)
  الکترون-ولت   
elektron-volt (#)

Fr.: électron-volt   

electron-volt.

electron; → volt.

electron-positron pair
  جفت ِ الکترون-پوزیترون   
joft-e elektron-pozitron (#)

Fr.: paire électron-positron   

The simultaneous formation of an → electron and a → positron in the → pair production process.

electron; → positron; → pair.

electron-scattering wing
  بال ِ پراکنش ِ الکترون   
bâl-e parâkaneš-e elektron

Fr.:   

A → line broadening phenomenon involving the scattering effect of → free electrons on the → radiation transfer in → stellar atmospheres. The scattering of radiation by free electrons plays an important role in the atmospheres of → hot stars, such as → O-types, early → B-types, and → Wolf-Rayet stars. The first detailed study of electron scattering in Wolf-Rayet stars was by Castor et al. (1970), who used electron scattering to explain the broad emission wings of N IV λ3483 in HD 192163. In → P Cygni stars the explanation of the very extended (almost symmetric) wings on the → Balmer lines as caused by electron scattering was first made by Bernat & Lambert (1978). Hillier (1991) showed that significant reduction in the strength of an electron-scattering wing can be achieved in a model of → clumped wind for a lower mean → mass loss rate. This resulted in a better agreement between observations and theoretical predictions. Electron-scattering wings provide diagnostics regarding the presence of density inhomogeneities in → stellar winds (Münch, 1948, ApJ 108, 116; Hillier, 1991, A&A 247, 455).

electron; → scattering; → wing.

electron-volt (eV)
  الکترون-ولت   
elektron-volt (#)

Fr.: électron-volt   

The energy acquired by an electron when accelerated through a → potential difference of 1 volt (1 eV = 1.602 × 10-12 → ergs = 11605 → kelvins).

electron; → volt.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer AGB air Alf Alg all alp alt AM amo ana And ang ani ano Ant Ant apa apo app app Ara Arc ari Arr ash ass ast ast asy atm ato att aut ave axi Bab bal Bal bar bar bea Bek Bes bia Big bin bin bip biv bla bli blu Boh Bol Bos bou bra bri bro buo cal cal can cap car Car cat cat CCD Cen cen CH cha cha che Che chr cir cir cit cla clo clo clu Coa coe coh col col col com com com com com com com com Com con con con con con con con con con con con con Cop Cor cor cor cos cos cou cou Cow cre cri cro cry cur cya Cyg dan dar dat de- deb dec dec ded def deg del dem den dep des det dev dia dif dif dih dio Dir dis dis dis dis dis dis DO don dou dow dro dur dwa dyn Dys ear ebb ecl edg egg Ein Ela ele ele ele ele ell eme emp enc eng ent epi equ equ equ esc eth Eur Eve exa exc exe exi exp exp ext ext ext fac fal far fed Fer fer fie fin fir fis fla flo flu fol for for fou fra fre Fre fro fut G-t gal gal gam gas Gau Gem gen geo geo geo gia Gli Gol gra gra gra gra gre gri gui H I Hag hal har hat He- hea hel Hel her Hes hie hig his hom hor hot Hub Hug hur hyd hyd hyg hyp ice ide ima Ima imp imp inc inc ind ine inf inf inf ing inn ins ins int int int int int int int int inv Io ion iro isl iso iso Jac jet jud jur Kel Kep kil Klo Kui Lag lam Lap Lar lat law lea len lep Lib lig lim lin lin Lio lit loc LOF lon Lor low lum lun Lup Lyo mac mag mag mag mag mag mai man Mar mas mas mat Max mea mec Meg Mer Mer met met Met mic Mid Mil min Mir mit mod mod mol mon Mor mou mul mul mys nan Nat nau nec neo neu nev New NGC no nom non non nor not nuc nuc num nut obj obs obs occ ocu oft ome Oor ope opp opt opt orb ord ori ort osc out ove oxi pai pan par par par par pas pea pen per per per per Per per pha phi pho pho pho phy pio Pla pla pla pla Pla plu Poi pol pol pol poo pos pos pot pra pre pre pre pre pri pri pro pro pro pro pro Pro pro pse pul pur qua qua qua qua que rac rad rad rad rad rad rad ran rar ray rea rea rec rec red red ref ref reg rel rel rel ren res res res res ret rev Ric rig rin roc roo rot rot Rus Sac sal sat sca sca Sch sci Scu sec sec Sed sel Sel sen ser Sex Sha she sho sid sig sil sim sin siz sla Sma sno sof sol sol sol sol sou sou spa spa spe spe spe sph spi spi spr squ sta sta sta sta ste ste ste Sto Str str str sub sub suc sun sup sup sup sup sur swa syn syn tab tar tek tem ter tes the the the the Tho thr tid tim Tis Too Tor tra tra Tra tra tra tri tri tru Tul tur two Typ ult un- und uni uni unk upp Urc utt val var vec vel ver vib vio vir vis voi vor wan wat wav wax wea Wei whi Wil win WN9 wor X-r yel you zer zod > >>