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

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 21 Search : formula
 Balmer formula   دیسول ِ بالمر   disul-e BâlmerFr.: formule de Balmer   A special solution of the mathematical formula which represents the wavelengths of the various spectral series of hydrogen in which the lower energy level is n = 2.→ Balmer; → formula. Bekenstein formula   دیسول ِ بکنشتاین   disul-e BekensteinFr.: formule de Bekenstein   The mathematical expression giving the → entropy, S, of a → black hole as a function of the area of its → event horizon, A: S = (kc3A)/(4Għ), where k is → Boltzmann's constant, ħ is the → reduced Planck's constant, and G the → gravitational constant. It can also be expressed by S = (kA)/(4lP2), where lP is the → Planck length. The existence of this entropy led to the prediction of the → Hawking radiation, because an entropy is associated with a temperature and a temperature to a → thermal radiation. The entropy of a black hole increases continuously because the fall of material into it increases its area.For Jacob D. Bekenstein (1947-), an Israeli theoretical physicist, who contributed to the foundation of black hole thermodynamics; → formula. Boltzmann's entropy formula   دیسول ِ درگاشت ِ بولتسمن   disul-e dargâšt-e BoltzmannFr.: formule d'entropie de Boltzmann   In → statistical thermodynamics, a probability equation relating the → entropy S of an → ideal gas to the quantity Ω, which is the number of → microstates corresponding to a given → macrostate: S = k. ln Ω. Same as → Boltzmann's relation.→ Boltzmann's constant; → entropy; → formula. compound angle formula   دیسول ِ زاویه‌ی ِ همنات   disul-e zaviye-ye hamnâtFr.: formule d'angle composé   One of eight equations that give the → trigonometric functions of → compound angles. sin(A± B) = sinA.cosnd angleB± cosA.sinB cos(A + B) = cosA.cosB - sinA.sinB cos(A - B) = cosA.cosB + sinA.sinB tan(A + B) = (tanA + tanB)/(1 - tanA.tanB) tan(A - B) = (tanA - tanB)/(1 + tanA.tanB).→ compound; → angle; → formula. Descartes' formula   دیسول ِ دکارت   disul-e DescartesFr.: formule de Descartes   A formula that gives the position of an image formed by highly → paraxial rays from a → spherical mirror. It is quite accurately given by: 1/xo + 1/xi = 2/xC, where xo is the distance along the → principal axis from the mirror to the object, xi is the distance from mirror to image, and xC is the distance from the mirror to its center of curvature. Any distance measured on the same side of the mirror as the reflecting surface is positive; on the other side, negative. Thus for a → concave mirror  xC is positive; for a → convex mirror, negative.→ Descartes; → formula. dimensional formula   دیسول ِ وامونی   disul-e vâmuniFr.: formule dimensionnelle   Symbolic representation of the definition of a physical quantity obtained from its units of measurement. For example, with M = mass, L = length, T = time, area = L2, velocity = LT-1, energy = ML2T-2. → dimensional analysis.→ dimensional; → formula. empirical formula   دیسول ِ آروینی   disul-e ârviniFr.: formule empirique   1) In physics, a mathematical equation that predicts observed results, but has no known theoretical basis to explain why it works. 2) In chemistry, a simple expression of the relative number of each type of atom in a chemical compound.→ empirical; → formula Euler's formula   دیسول ِ اویلر   disul-e EulerFr.: formule d'Euler   A formula which expresses an → exponential function with an → imaginary number  → exponent in terms of → trigonometric functions: eiθ = cos θ + i sinθ, e-iθ = cos θ - i sinθ, cosθ = (eiθ + e-iθ)/2, sinθ = (eiθ - e-iθ)/2i. In the particular case of θ = π, Euler's formula becomes: eiπ + 1 = 0, which is considered by many mathematicians to be the most elegant mathematical equation. → mathematical elegance.→ Euler; → formula. formula   دیسول   disulFr.: formule   1) Physics, Math.: A statement of facts in a symbolical or general form, by substitution in which a result applicable to particular data may be obtained. 2) Chemistry: An expression of the constituents of a compound by symbols and figures.From L. formula "form, rule, method, formula," literally "small form," from forma, → form, + → -ule diminutive suffix.Disul, from dis, → form, + -ul, → -ule. formulate   دیسولیدن   disulidanFr.: formuler   To express in precise → form; state definitely or systematically. To reduce to or express in a → formula.Verbal form of → form. formulation   دیسولش   disulešFr.: formulation   1) The act or process of formulating. 2) A particular expression of an idea, thought, or theory. 3) Something prepared according to a → formula.→ formulate; → -tion. mass formula   دیسول ِ جرم   disul-e jermFr.: formule de masse   An → equation expressing the → atomic mass of a → nuclide as a function of its → mass number and the → atomic mass unit.→ mass; → formula. molecular formula   دیسول ِ مولکولی   disul-e molekuliFr.: formule moléculaire   The formula of a chemical compound, showing the kind and arrangement of atoms.→ molecular; → formula. Newton-Leibniz formula   دیسول ِ نیوتن-لایبنیتس   disul-e Newton-LeibnizFr.: formule de Newton-Leibniz   The formula expressing the value of a → definite integral of a given function over an interval as the difference of the values at the end points of the interval of any → antiderivative of the function: ∫f(x)dx = F(b) - F(a), summed from x = a to x = b.Named after Isaac → Newton and Gottfried Wilhelm Leibniz (1646-1716), who both knew the rule, although it was published later; → formula. Nyquist formula   دیسول ِ نیکویءیست   disul-e NyquistFr.: formule de Nyquist   The mean square noise voltage across a resistance in thermal equilibrium is four times the product of the resistance, Boltzmann's constant, the absolute temperature, and the frequency range within which the voltage is measured. → Johnson-Nyquist noise.Named after Harry Nyquist (1889-1976), a Swedish-born American physicist, who made important contributions to information theory. → Johnson-Nyquist noise; → formula. Planck's blackbody formula   دیسول ِ سیه‌جسم ِ پلانک   disul-e siyah jesm-e PlanckFr.: formule du corps noir de Planck   A formula that determines the distribution of intensity of radiation that prevails under conditions of thermal equilibrium at a temperature T: Bv = (2hν3 / c2)[exp(hν / kT) - 1]-1 where h is Planck's constant and ν is the frequency.→ Planck; → blackbody; → formula. quadratic formula   دیسول ِ چاروشی   disul-e cârušiFr.: formule quadratique   A formula relating the unknown part of a → quadratic equation (the roots of the equation, x) to the known parts (a, b, and c): x = (-b± (b2 - 4ac)½) / 2a.→ quadratic; → formula. Rydberg formula   هموگش ِ رودبَری   hamugeš-e RydbergFr.: formule de Rydberg   A formula, used in atomic physics, which describes the wavelengths or frequencies of light in various series of related spectral lines, such as those emitted by hydrogen atoms.→ rydberg; → formula. semiempirical binding energy formula   دیسول ِ نیمه‌آروینی ِ انرژی ِ بندش   disul-e nime-ârvini-ye kâruž-e bandešFr.: formule semi-empirique de l'énérgie de liaison   Same as → Weizsacker formula.→ semiempirical; → binding; → energy; → formula. Weizsacker formula   دیسول ِ وایتسکر   disul-e WeizsäckerFr.: formule de Weizsäcker   A → semiempirical → equation which describes the → binding energy of the → atomic nucleus. It is essentially a nuclear mass formula that provides the total binding energy per → nucleon as the sum of five terms: Eb = aVA - aSA2/3 - aCZ2/A1/3 - aA(N -Z)2/A + δ(A,Z), where the terms in the right-hand side of this equation are called the volume term, surface term, Coulomb term, asymmetry term, and pairing term, respectively. A, Z, and N are the number of nucleons, → protons, and → neutrons, respectively (see, e.g., Alexi M. Frolov, 2013, arxiv.org/pdf/1212.6768). Also called Bethe-Weizacker formula and → semiempirical binding energy formula.Named after Carl Friedrich von Weizäcker (1912-2007), German physicist, who derived the formula in 1935, Z. für Physik 96, 431; → formula.

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