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edition 1) virâyeš (#); 2) virâst (#) Fr.: édition 1) The act or process of editing. Verbal noun of → edit. |
education farhizeš (#) Fr.: éducation The act or process of educating. Verbal noun of → educate. |
effective Eddington parameter pârâmun-e Eddington-e oskarmand Fr.: paramètre d'Eddington effectif The effective value of the → Eddington parameter in a non-homogeneous system (porous opacity). → effective; → Eddington limit; → parameter. |
eigenfunction viž-karyâ Fr.: fonction propre 1) Math.: An → eigenvector for a linear
→ operator on a → vector space
whose vectors are → functions. Also known as
proper function. From Ger. Eigenfunktion, from eigen- "characteristic, particular, own" (from P.Gmc. *aigana- "possessed, owned," Du. eigen, O.E. agen "one's own") + → function. Viž-karyâ, from viž, contraction of vižé "particular, charcteristic" + karyâ, → function. Vižé, from Mid.Pers. apēcak "pure, sacred," from *apa-vēcak "set apart," from prefix apa- + vēcak, from vēxtan (Mod.Pers. bixtan) "to detach, separate, sift, remove," Av. vaēk- "to select, sort out, sift," pr. vaēca-, Skt. vic-, vinakti "to sift, winnow, separate; to inquire." |
Einstein notation namâdgân-e Einstein Fr.: convention Einstein A notation convention in → tensor analysis whereby whenever there is an expression with a repeated → index, the summation is done over that index from 1 to 3 (or from 1 to n, where n is the space dimension). For example, the dot product of vectors a and b is usually written as: a.b = Σ (i = 1 to 3) a_{i}.b_{i}. In the Einstein notation this is simply written as a.b = a_{i}.b_{i}. This notation makes operations much easier. Same as Einstein summation convention. |
Einstein's field equations hamugešhâ-ye meydân-e Einstein Fr.: équations de champ d'Einstein A system of ten non-linear → partial differential equations in the theory of → general relativity which relate the curvature of → space-time with the distribution of matter-energy. They have the form: G_{μν} = -κ T_{μν}, where G_{μν} is the → Einstein tensor (a function of the → metric tensor), κ is a coupling constant called the → Einstein gravitational constant, and T_{μν} is the → energy-momentum tensor. The field equations mean that the curvature of space-time is due to the distribution of mass-energy in space. A more general form of the field equations proposed by Einstein is: G_{μν} + Λg_{μν} = - κT_{μν}, where Λ is the → cosmological constant. Named after Albert Einstein (1879-1955); → field; → equation. |
Einstein's gravitational constant pâyâ-ye gerâneši-ye Einstein (#) Fr.: constante gravitationnelle d'Einstein The coupling constant appearing in → Einstein's field equations, expressed by: κ = 8πG/c^{4}, where G is the Newtonian → gravitational constant and c the → speed of light. → einstein; → gravitational; → constant. |
Einstein-Hilbert action žireš-e Einstein-Hilbert Fr.: action de Einstein-Hilbert In → general relativity, the → action
that yields → Einstein's field equations.
It is expressed by: → Einstein; → Hilbert space; → action. |
ejection ešâneš Fr.: éjection Act or instance of ejecting; the state of being ejected. Verbal noun of → eject. |
elastic collision hamkubš-e kešâyand Fr.: collision élastique A collision between two particles which conserves the total kinetic energy and momentum of the system. |
elastic deformation vâdiseš-e kešâyand Fr.: déformation élastique A deformation of a → solid body in which the change (→ strain) in the relative position of points in the body disappears when the deforming stress is removed. See also → elastic limit. → elastic; → deformation. |
electrical conductivity hâznadegi-e barqi Fr.: conductivité électrique A measure of a material's ability to conduct an electrical current. It is the reciprocal of the → resistivity. Conductivity is expressed by σ = ne^{2}l/(2mv), where n is the number of electrons per cm^{3} volume of the → conductor, e is the → electron charge, l is the → mean free path, m is the → electron mass, and v is the arithmetic mean velocity of thermal motion of electrons at a given temperature. → electrical; → conductivity. |
electromagnetic induction darhâzeš-e barqâmeqnâti Fr.: induction électromagnétique The production of an → electromotive force in a circuit caused by a variation in the magnetic flux through the circuit. If this variation is produced by a change in the current flowing in the circuit itself, it is called → self-induction. If due to the variation in a current in some other circuit, it is called mutual induction. See also → Faraday's law of induction. → electromagnetic; → induction. |
electromagnetic radiation tâbeš-e barqâmeqnâti Fr.: rayonnement électromagnétique Radiation propagating in the form of an advancing wave in electric and magnetic fields. It includes radio waves, infrared, visible light, ultraviolet, X-rays, and gamma rays. → electromagnetic; → radiation. |
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 affinity 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 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, 1s^{2} 2s^{2} 2p^{3} 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. |
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