An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

In photochemistry, the number of defined events which occur per photon absorbed by the system.

→ quantum; → theory.

1a) Chemistry: The quantity of product resulting from a chemical reaction or process, generally expressed as a percentage of the amount that is theoretically obtainable.
1b) Nuclear physics: 1) The number of → daughter atoms produced by the decay of one atom of a → parent radioactive element. For example, the → fission of one atom of ²³⁸U produces an average 0.0063 atoms of ¹³⁶Xe, denoted: Y (¹³⁶Xe)₂₃₈ = 0.0063.
1c) A measure of the destructive energy of a nuclear explosion, expressed in kilotons of the amount of → T.N.T. that would produce the same destruction.
1d) → quantum yield.
2) → yield point.

M.E.; O.E. geldan, gieldan "to pay;" cf. O.S. geldan "to be worth," M.Du. ghelden, Du. gelden "to cost, be worth," O.H.G. geltan, Ger. gelten "to be worth."

1) Bâzdeh "yield, return," from bâz- "anew, again," → re- + deh present stem of dâdan "to give" (Mid.Pers. dâdan "togive, create;" O.Pers./Av. dā- "to give, grant, yield," dadāiti "he gives;" Skt. dadáti "he gives;" Gk. tithenai "to place, put, set," didomi "I give;" L. dare "to give, offer," facere "to do, to make;" Rus. delat' "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do;" PIE base *dhe- "to put, to do").
2) Vâdehi, vâdâd, verbal noun from vâdâdan "to surrender," from vâ-, → de-, + dehi, dâd, from dâdan, as above.

The point at which the → strain caused by a → stress on a material begins to increase without further increase in the stress. This point marks the end of → elastic deformation and the beginning of → plastic deformation. Same as → elastic limit.

→ yield; → point.