| 释义 |
▪ I. ab-
prefix repr. L. ab, prep. ‘off, away, from,’ cogn. w. Gr. ἀπό, Skr. apa, OTeut. af, OE. of, mod.E. of, off, mod.G. ab. In L. it was reduced to a- before p-, m-, and v-, became au- before f-, and abs- before c- and t-. The form ab- was in OFr. generally retained as in abusum, abus; sometimes changed to av- as in abortionem, avortion; sometimes reduced to a- as in abbreviāre, abregier, abridge. Ab- appears in Eng. in words that have lived on through OFr. as abuse; that have been adapted or formed in later Fr. as absorb; or have been adapted or formed in Eng. as ablaqueate, abhominal, abarticulation. Quite recent, and apparently suggested by ab-normal, are formations like ab-oral, ab-actinal, in which ab- is used for ‘position away from.’
▪ II. ab-, prefix2 Electr. rare.|æb|
[Shortened form of absolute a.]
Prefixed to the names of practical units (predecessors of SI units) of electrical and magnetic quantities to form the names of corresponding units in the CGS electromagnetic system, as abampere, abcoulomb, abfarad, abhenry, abohm, abvolt.
q1905W. Duddell in Jrnl. Inst. Electr. Engin. XXXIV. 172 The second proposition of Dr. Kennelly was that names should be given to each of the C.G.S. units in both the magnetic and the static systems, and he suggested that the prefix ab or abs should be used with the names of the practical units (Volt, Ampere, Ohm, etc.), to form names for the corresponding C.G.S. electromagnetic units, and the prefix abstat to form the names for the C.G.S. electrostatic units. 1909Cent. Dict. Suppl., Abcoulomb. Ibid., Abfarad. Ibid., Abhenry. 1930A. Zeleny Elem. Electr. 402 The abcoulomb is the quantity of electricity that passes any plane in a circuit in 1 second when the current is 1 abampere. 1940F. A. Fish Fund. Princ. Electr. & Magn. Circuits (ed. 3) iii. 28 The absolute unit, or abvolt, is that e.m.f. which will cause 1 abampere of current to flow in 1 abohm of resistance. Ibid. iv. 90 If es is expressed in abvolts, and i is in abamperes, L is given in abhenries; the abhenry is, therefore, equal to 1 henry divided by 109. 1963Jerrard & McNeill Dict. Sci. Units 13 The inconvenience of having three systems of electrical units, ab units, stat units and practical units has been overcome by the introduction of the metre, kilogramme, second, ampere units. 1966McGraw-Hill Encycl. Sci. & Technol. I. 332/1 The abampere (10 amperes) is seldom used. 1970Amer. Jrnl. Physics XXXVIII. 421 The relationships among corresponding symbols are given and applied to precise statements about the relation between the oersted and the ampere per meter, the abampere and the ampere, etc. |