Elektronvolt: Verskil tussen weergawes

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Nuwe blad: Die '''elektronvolt''' (simbool '''eV''') is 'n eenheid van energie. Dit is die hoeveelheid kinetiese energie wat 'n enkele onverbonde elektron verkry as dit deur 'n [[Elektr...
 
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Lyn 4:
: 1 eV = 1.602 176 53 e<sup>−19</sup> [[joule|J]]. <ref>Peter J. Mohr en Barry N. Taylor, CODATA recommended values of the fundamental physical constants: 2002, Reviews of Modern Physics, January 2005, volume=77 bladsye=1&ndash;107, [http://www.atomwave.org/rmparticle/ao%20refs/aifm%20refs%20sorted%20by%20topic/other%20rmp%20articles/CODATA2005.pdf PDF] afgelaai op 2006-07-01, 'n In diepte bespreking oor hoe die CODATA konstantes gekies en bepaal is.</ref> (of ongeveer 0.160 [[atto|a]]J)
 
Die elektronvolt as eenheid word deur die [[SI]] aanvaar (maar nie aangemoedig nie). Dit word algemeen gebruik in [[Vastetoestandfisika|Vastetoestand-]], [[Kernfisika|Kern-]] en [[partikelfisika]], dikwels saam met die [[SI#SI-voorvoegsels|voorvoegsels]] m, k, M, G of T.
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The unit electronvolt is accepted (but not encouraged) for use with [[SI]]. It is widely used in [[Solid-state physics|solid state]], [[Atomic physics|atomic]], [[Nuclear physics|nuclear]], and [[particle physics]], often with [[SI prefix|prefixes]] m, k, M, G or T. In a recorded lecture from 1961 [[Richard Feynman]] apologised to his students for this failure by atomic physicists to use the appropriate SI unit (which would be the [[atto]]joule):
:''"Nearly a third of what you have to learn consists of different ways of measuring the same thing, and I apologize for it ... A single atom is such a small thing that to talk about its energy in joules would be inconvenient. But instead of taking a definite unit in the same system (like 10{{e|-20}} J), [physicists] have unfortunately chosen, arbitrarily, a funny unit called an electronvolt (eV) ... I am sorry that we do that, but that's the way it is for the physicists."'' <ref>[http://home.att.net/~numericana/answer/feynman.htm Transcription of part of a 1961 lecture by Richard Feynman]</ref>
 
[[Ionisasie energie]]ë en ander atoomeienskappe word dikwels aangehaal in terme van elektronvolt, veral in ouer tekste.
In [[chemistry]], it is often useful to have the molar equivalent, that is the kinetic energy that would be gained by a [[mole (unit)|mole]] of electrons passing through a potential difference of one volt. This quantity is equal to [[1 E4 J|96.48538(2)]]&nbsp;[[Joule per mole|kJ/mol]]. [[Ionization energy|Ionization energies]] and other atomic properties are often quoted in electronvolts, especially in older texts.
 
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==Using electronvolts to measure mass==
[[Albert Einstein]] reasoned that energy is equivalent to [[mass]], as famously expressed in the [[mass-energy equivalence]] formula ''E'' = ''mc''² (1.0000 [[kilogram|kg]] = 89.876 [[petajoule|PJ]]). It is thus common in particle physics, where mass and energy are often interchanged, to use eV/''c''² or even simply eV as a unit of mass.