Fr.: énergie radiative
šâr-e tâbeši (#)
Fr.: flux radiatif
Rate of flow of energy as → radiation.
Fr.: intensité de rayonnement
A measure of the amount of radiation emitted from a point expressed as the radiant flux per unit solid angle leaving this source.
From L. radiat(us), p.p. of radiare "to shine, to beam" + -ate verbal suffix.
Tâbidan, variants tâftan "to shine," tafsidan "to become hot;" Mid.Pers. tâftan "to heat, burn, shine;" taftan "to become hot;" Parthian t'b "to shine;" Av. tāp-, taf- "to warm up, heat," tafsat "became hot," tāpaiieiti "to create warmth;" cf. Skt. tap- "to heat, be/become hot; to spoil, injure, damage; to suffer," tapati "burns;" L. tepere "to be warm," tepidus "warm;" PIE base *tep- "to be warm."
Fr.: radiation, rayonnement
Verbal noun of → radiate.
kamarband-e tâbeš (#), ~ tâbeši (#)
Fr.: ceinture de radiations
A ring-shaped region in the → magnetosphere of a planet in which charged particles are trapped by the planet's magnetic field. The radiation belts surrounding Earth are known as the → Van Allen belts.
Fr.: constante de rayonnement
Same as → radiation density constant.
Fr.: amortissement par rayonnement
Damping of a system which loses energy by → electromagnetic radiation.
radiation density constant
pâypa-ye cagâli-ye tâbeš
Fr.: constante de rayonnement
The constant related to the total energy radiated by a → blackbody and defined as: a = 4σ/c, where σ is the → Stefan-Boltzmann constant and c the → speed of light. Its value is a = 7.5657 x 10-15 erg cm-3 K-4. Same as → radiation constant.
Fr.: ère du rayonnement
The epoch in the history of the Universe, lasting from the → Big Bang until about 400,000 years later, when the temperature had dropped to 109 K and the rate of electron-positron → pair annihilation exceeded the rate of their production, leaving radiation the dominant constituent of the Universe. The radiation era was followed by the → matter era.
Fr.: champ de rayonnement
1) The portion of an → electromagnetic field outside the
→ induction field where there is a power flow of both
→ magnetic and → electric
components in a well-defined relationship.
Fr.: longueur de rayonnement
The mean distance traveled by a photon or particle in a given medium before its energy is reduced by a factor e due to its interaction with matter.
Fr.: diagramme de rayonnement
Same as → antenna pattern.
Fr.: pression de radiation
The → momentum carried by → photons to a surface exposed to → electromagnetic radiation. Stellar radiation pressure on big and massive objects is insignificant, but it has considerable effects on → gas and → dust particles. Radiation pressure is particularly important for → massive stars. See, for example, → Eddington limit, → radiation-driven wind , and → radiation-driven implosion. The → solar radiation pressure is also at the origin of various physical phenomena, e.g. → gas tails in → comets and → Poynting-Robertson effect.
Fr.: mal des rayons
An illness resulting from excessive exposure to ionizing radiation. The earliest symptoms are nausea, vomiting, and diarrhea, which may be followed by loss of hair, hemorrhage, inflammation of the mouth and throat, and general loss of energy.
→ radiation; sickness, M.E. siknesse, seknesse; O.E. sēocnesse, from seoc + suffix -ness.
Bimâri "sickness, infirmity, disease," from bimâr "sick, infirm, afflicted;" Mid.Pers. vêmâr "sick, ill;" maybe by corruption of Proto-Iranian *amavayā-bara- "bearing illness;" cf. Av. amavayā- "pain, suffering, affliction;" Skt. ámīvā- "pain, grief, distress" + *bara- "bearing;" cf. Av. bar- "to bear, carry;" Mod.Pers. bar-, bordan "to bear, carry, lead." Alternatively, from *vi-mar-, prefixed *mar- "to die;" cf. Av. mar- "to die;" Mod.Pers. mir-, mordan "to die;" Skt. mar- "to die;" cognate with Gk. emorten "died;" L. morior "to die;" tâbeši related to tâbeš, → radiation.
Fr.: spectre de rayonnement
The components of radiation arranged in order of their wavelengths, frequencies, or quantum energies. For particle radiation they are arranged in order of their kinetic energies.
Fr.: température de rayonnement
The temperature of a source calculated assuming that it behaves as a → blackbody that radiates with the same intensity at the same frequency. Compared to the → effective temperature, the radiation temperature is measured over a narrow region of the → electromagnetic spectrum.
Fr.: transfert radiatif, ~ de rayonnement
radiation transfer equation
hamugeš-e tarâvâž-e tâbeš
Fr.: équation de transfert radiatif, ~ de rayonnement
Fr.: Univers dominé par le rayonnement
An early epoch in the history of the → Universe when the radiation → density parameter was Ωr≈ 1, while other density parameters had negligible contributions. A radiation-dominated Universe is characterized by R/R0 ∝ t1/2, where R is the → cosmic scale factor and t is time. According to the → Big Bang model, the radiation-dominated phase was followed by the → matter-dominated phase.