lepton number adad-e leptoni (#) Fr.: nombre leptonique In particle physics, a quantum number attributed to elementary particles which is conserved in nuclear reactions. It is +1 for a lepton, -1 for an antilepton and 0 for other particles. |
Loschmidt's number adad-e Loschmidt Fr.: nombre de Loschmidt The number of molecules in 1 cm^{3} of an ideal gas (2.687 x 10^{19} per cm^{3}). Joseph Loschmidt (1821-1895), Austrian physicist. |
Mach number adad-e Mach (#) Fr.: nombre de Mach The ratio of the speed of a moving object to the → sound speed in the medium through which the object is traveling. Named after the Austrian physicist Ernst Mach (1838-1916); → number. |
magnetic Prandtl number adad-e Prandtl-e meqnâtisi Fr.: nombre de Prandtl magnétique A → dimensionless quantity used in → magnetohydrodynamics to describe the relative balance of → kinematic viscosity to → magnetic diffusion. It is described by: P_{r} = σμ_{0}ν = ν/η, where σ is the → conductivity of the fluid, μ_{0} is the → magnetic permeability of the fluid, ν is the kinematic viscosity of the fluid, and η is the → magnetic diffusivity. → magnetic; → Prandtl number. |
magnetic quantum number adad-e kuântomi-ye meqnâtisi (#) Fr.: nombre quantique magnétique In atomic physics, a quantum number that denotes the energy levels available within a subshell. Designated by the letter m, it is one of a set of quantum numbers which describe the unique quantum state of an electron. |
magnetic Reynolds number adad-e Reynolds-e meqnâtisi Fr.: nombre de Reynolds magnétique A → dimensionless quantity used in → magnetohydrodynamics to describe the relative balance of → magnetic advection to → magnetic diffusion. It is given by: R_{m} = σμ_{0}νLU_{0}, where σ is the → conductivity of the fluid, μ_{0} is the → magnetic permeability of the fluid, L is he characteristic length scale of the fluid flow, and U_{0} the characteristic velocity of the flow. A typical value for the Earth is R_{m} ~ 200. → magnetic; → Reynolds number. |
mass number adad-e jermi (#) Fr.: nombre de masse The total number of → protons and → neutrons in the → atomic nucleus (symbol A). The mass number is written either after the → chemical element name or as a superscript to the left of an element's symbol. For example, the most common isotope of oxygen is oxygen-16, or ^{16}O, which has 8 protons and 8 neutrons. |
natural number adad-e zâstâri Fr.: nombre naturel Either a member of the set of positive integers 1, 2, 3, ..., or the set of non-negative integers 0, 1, 2, 3, ... There seems to be no general agreement about whether to include 0 in the set of natural numbers. |
negative number adad-e nâyidâr Fr.: nombre négatif A → real number that is less than zero. A negative number is indicated by the → minus sign. |
number 1) adad (#), šomâré (#); 2) šomâr (#) Fr.: 1) nombre, numéro; 2) numéro 1) Any real or complex numeral quantity. From M.E. nombre, from O.Fr. nombre, from L. numerus "a number, quantity," from PIE base *nem- "to divide, distribute, allot." Adad, loan from Ar. |
number density cagâli-ye adadi Fr.: densité nmérique Number of a particular type of object found in each unit volume. |
number e 'adad-e e Fr.: nombre e The → base of the → natural logarithm. It is defined as: e = lim (1 + 1/n)^{n} when n→ ∞. For n = 1, e = 2 and for n = 10, e = 2.5937424601, etc. The number e is → irrational (Euler, 1737) and → transcendental (Hermite, 1873). → number; |
number pi adad-e pi (π) Fr.: nombre pi (π) Symbol, π, for the ratio of the circumference of a circle to its diameter in Euclidean geometry; a fundamental mathematical constant, equal to 3.14159... π is an → irrational number (Lambert, 1761) and also a → transcendental number (von Lindemann, 1882). The most accurate determination of π prior to the Scientific Revolution belongs to the Iranian mathematician Jamshid Kashani, who gave 16 correct decimal places in A.D. 1424. With the advent of → calculus and more recently the invention of powerful computers, the decimal representation of π has now been computed to more than 10^{12} digits. The π notation, representing the first letter of the Gk. word περιμετρον → perimeter, was first used by the British mathematician William Jones (1675-1749) in 1706. Its use was generalized after its adoption by the Swiss mathematician Leonard Euler (1707-1783) in 1737; → number. |
number system râžmân-e adadhâ, ~ adadi Fr.: système de numération Same as → numeral system. |
number system conversion hâgard-e râžmân-e adadi Fr.: conversion de système de numération The conversion of a → number system
with a given → base to another system with a
different base; such as the conversion of a → decimal number
(base 10) to a → binary number system
(base 2).
In order to convert a number into its representation in a different
number base, we have to express the number in terms of powers of the other base.
For example, to convert the decimal number 100 to base 3, we must figure out how to
express 100 as the sum of powers of 3. We proceed as follows: → number; → system; → conversion. |
number theory negare-ye adadhâ Fr.: théories des nombres The branch of mathematics that studies the relationship between integers and their generalization. |
ordinal number adad-e râye-yi Fr.: nombre ordinal 1) A number which defines the position or rank of something in a series, in contrast to
→ cardinal number. For example, first,
second, tenth, etc. |
oxidation number šomâr-e oksâyeš Fr.: nombre d'oxydation The total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom. In other words, the charge that atom would have if the compound was composed of ions. The oxidation number of an atom is zero in a neutral substance that contains atoms of only one element. Same as → oxidation state. |
perfect number adad-e farsâxt Fr.: nombre parfait An → integer that is equal to the → sum of its → positive → divisors, not including itself. For example 6, because its positive divisors are 1, 2, and 3, and 1 + 2 + 3 = 6. Two other examples are 28 and 496. |
pi number adad-e pi (π) Fr.: nombre pi (π) Symbol, π, for the ratio of the circumference of a circle to its diameter in Euclidean geometry; a fundamental mathematical constant, equal to 3.14159... π is an → irrational number (Lambert, 1761) and also a → transcendental number (von Lindemann, 1882). The most accurate determination of π prior to the Scientific Revolution belongs to the Iranian mathematician Jamshid Kashani, who gave 16 correct decimal places in A.D. 1424. With the advent of → calculus and more recently the invention of powerful computers, the decimal representation of π has now been computed to more than 10^{12} digits. The π notation, representing the first letter of the Gk. word περιμετρον → perimeter, was first used by the British mathematician William Jones (1675-1749) in 1706. Its use was generalized after its adoption by the Swiss mathematician Leonard Euler (1707-1783) in 1737; → number. |