# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

Homepage

<< < die Gau > >>

Number of Results: 34 Search : electric
 Gauss's law for electricity   قانون ِ گاؤس در برق   qânun-e Gauss dar barqFr.: loi de Gauss en électricité   The total electric flux ψ out of an arbitrary closed surface in free space is equal to the net charge within the surface divided by the → permittivity. In differential form: ∇ . E = ρ/ε0, where ρ is the → charge density and ε0 the permittivity. The integral form of the law: ∫E . dS = Q/ε0 (closed surface integral). This is one of the four → Maxwell's equations.→ gauss; → law; → electricity. induced electric field   میدان ِ برقی ِ درهازیده، ~ ِ ~ ِ درهاخته   meydân-e barqi-ye darhâzidé, ~ ~ darhâxtéFr.: champ électric induit   An electric field created by the variation of a magnetic field. The induced electric field lines are usually perpendicular to the changing magnetic field that produces them.→ induced; → electric; → field. internal photoelectric effect   اسکر ِ شید-برقی ِ درونی   oskar-e šid-barqi-ye daruniFr.: effet photoélectrique interne   The → photoelectric effect whereby photons absorbed by a solid (→ semiconductor) raise electrons from a lower to a higher → energy level (from → valence band to → conduction band). See also → external photoelectric effect.→ internal; → photoelectric; → effect. linear electric quadrupole   چهارقطبه‌ی ِ برقی ِ خطی   cahârqotbe-ye barqi-ye xattiFr.: quadrupôle électrique linéaire   A system of three charges +q, -2q, and +q, arranged along a line to form an axial quadrupole. The → electric potential  V due to a linear quadrupole varies as 1/r3, whereas the → electric intensity  E varies as 1/r4.→ linear; → electric; → quadrupole. photoelectric   شید-برقی، نور-برقی   šid-barqi, nur-barqiFr.: photoélectrique   Pertaining to electronic or other electrical effects that are due to the action of electromagnetic radiation, especially visible light.→ photo- + → electric. photoelectric current   جریان ِ شید-برقی   jarayân-e šid-barqiFr.: courant photoélectrique   The current produced in an → photoelectric effect process when → photoelectrons are received at the positive electrode.→ photoelectric; → current. photoelectric effect   ا ُسکر ِ شید-برقی، ~ نور-برقی   oskar-e šid-barqi, ~ nur-barqiFr.: effet photoélectrique   The process of release of electrically charged particles (usually → electrons) as a result of irradiation of matter by light or other → electromagnetic radiation. The classical electromagnetic theory was unable to account for the following characteristics of the phenomenon. Light below a certain threshold frequency, no matter how intense, will not cause any electrons to be emitted. Light above that frequency, even if it is not very intense, will always cause electrons to be ejected. The electrons are ejected after some nanoseconds, independently of the light intensity. The maximum kinetic energy of the emitted electrons is a function of the frequency and does not dependent on the intensity of the incident light. The classical theory could not explain how a train of light waves spread out over a large number of atoms could, in a very short time interval, concentrate enough energy to knock a single electron out of the metal. In 1905, based on Planck's idea of → quanta, Einstein proposed that light consisted of quanta (later called → photons); that a given source could emit and absorb radiant energy only in units which are all exactly equal to the radiation frequency multiplied by a constant (→ Planck's constant); and that a photon with a frequency over a certain threshold would have sufficient energy to eject a single electron. His photoelectric equation is descibed as (1/2)mu2 = hν - A, where m is the electron mass, u is the electron velocity, h is Planck's constant, ν is the frequency, and A the → work function, which represents the amount of work needed by electrons to get free of the surface. See also → photoelectron, → photoelectric current, → external photoelectric effect, → internal photoelectric effect.→ photoelectric; → effect. photoelectric heating   گرمایش ِ شید-برقی   garmâyeš-e šid-barqiFr.: chauffage photoélectrique   A heating process occurring in → diffuse molecular clouds which is believed to be the main heating mechanism in cool → H I regions. Far-ultraviolet (FUV) photons, in the energy range 6 eV

<< < die Gau > >>