Fr.: échande de charge
A collisional process in which an → ion collides with a neutral → atom or → molecule and captures one of its electrons. One of the most important charge-exchange processes occurring in the → interstellar medium is: O+ + H → H+ + O + 0.020 eV.
1) gahulidan (#); 2) gahul, gahuleš
Fr.: 1) échanger; 2) échange
1) To give and receive reciprocally.
O.Fr. eschangier, from V.L. *excambiare, from L. → ex- "out" + cambire "barter."
Mod.Pers. gahulidan "to exchange," Kurd. guhartin/guhêr- "to exchange," Mid.Pers. wihir "to change," wihirišn "change," Manichean Mid.Pers. hr'g; Buddhist Mid.Pers. hlg "duty, tribute; work, effort;" Arm. loanword hark "duty, tribute;" Ar. loanword xarj "expense," xarâj "land, property tax;" Proto-Iranian *har- "to barter, trade; to pay tribute;" IE cognates: Gk. elein "to take (by force)," elor "loot, booty, catch;" Goth. saljan "to bring, to sacrifice;" O.E. sellan "to hand over, sell;" O.H.G. sala "delivery of goods."
Fr.: force d'échange
The force that governs the exchange of particles in the interaction between bodies. → exchange particle.
Fr.: particule d'échange
In quantum field theory, a particle that transfers momentum and energy between interacting objects, and is said to mediate the interaction. All four of the fundamental forces involve the exchange of one or more particles. For example, photon is the exchange particle of the electromagnetic force.
Prevost's law of exchanges
qânun-e gahuleš-e Prévost
Fr.: loi des échanges de Prévost
A statement concerned with thermodynamic heat exchange, according to which bodies in → thermal equilibrium are simultaneously absorbing and emitting radiant energy. A body radiates in the same way whether other bodies are present or not. Also called Prevost's theory of exchanges.
Named after Pierre Prévost (1751-1839), a Swiss philosopher and physicist, who, in 1791, put forward the statement; → law; → exchange.