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SI brochure, from section 4.1
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| Name |
Symbol |
Definition |
Value in SI units |
| |
| electronvolt (a) |
eV |
(b) |
1 eV = 1.602 177 33 (49) x 10–19 J |
| unified atomic mass unit |
u |
(c) |
1 u = 1.660 540 2 (10) x 10–27 kg |
| astronomical unit |
ua |
(d) |
1 ua = 1.495 978 706 91 (30) x 1011 m |
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(a) For the electronvolt and the unified atomic mass unit, values are quoted from CODATA Bulletin, 1986, No. 63.
The value given for the astronomical unit is quoted from the IERS Conventions (1996), D.D. McCarthy ed., IERA Technical Note 21, Observatoire de Paris, July 1996.
(b) The electronvolt is the kinetic energy acquired by an electron in passing through a potential diference of 1 V in vacuum.
(c) The unified atomic mass unit is equal to 1/12 of the mass of an unbound atom of the nuclide 12C, at rest, and in its ground state. In the field of biochemistry, the unified atomic mass unit is also called the dalton, symbol Da.
(d) The astronomical unit is a unit of length approximately equal to the mean Earth-Sun distance. Its value is such that, when used to describe the moton of bodies in the Solar System, the heliocentric gravitational constant is (0.017 202 098 95)2 ua3 · d–2.
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