<< < -en ear eav ecl edd eff Ein El ele ele ele ele Eln emi emp ene eni ent epi equ equ Eri est Euc eva evo exc exc exi exp exp ext ext eye > >>
electromagnetic theory of light 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 mowj-e barqâmeqnâti Fr.: onde électromagnétique A wave produced by oscillation or acceleration of an electric charge. → electromagnetic radiation. → electromagnetic; → wave. |
electromagnetism barqâmeghnât, barqâmeghnâtis Fr.: électromagnétisme 1) The science dealing with the physical relations between → electricity
and → magnetism. Same as
→ electromagnetic theory. |
electromotive force (EMF) 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 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 capture 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 charge bâr-e elektron (#) Fr.: charge de l'électron The charge of one electron, e = -1.602 176 × 10-19→ coulombs or -4.803 204 51 × 10-10→ statcoulombs. |
electron configuration 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 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 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 diffraction 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 jerm-e elekron (#) Fr.: masse de l'électron The mass of an electron, which is 9.109 382 91 × 10-28 g. |
electron radius 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 shell 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 temperature 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). → electron; → temperature. |
electron volt (eV) elektron-volt (#) Fr.: électron-volt |
electron-positron pair joft-e elektron-pozitron (#) Fr.: paire électron-positron The simultaneous formation of an → electron and a → positron in the → pair production process. |
electron-scattering wing 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) 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). |
electronic 1) elektroni (#); 2) elektronik (#) Fr.: électronique 1) Of or relating to electrons or to an electron. |
<< < -en ear eav ecl edd eff Ein El ele ele ele ele Eln emi emp ene eni ent epi equ equ Eri est Euc eva evo exc exc exi exp exp ext ext eye > >>