# Council Directive of 20 December 1979 on the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC (80/181/EEC), Division 3: UNITS USED WITH THE SI, WHOSE VALUES IN SI ARE OBTAINED EXPERIMENTALLY

Extent: E+W+S+N.I.

Quantity
Unit
Name
Symbol
Definition
Energy
Electronvolt
eV
The electron volt is the kinetic energy acquired by an electron in passing through a potential difference of 1 volt in vaccum
Mass
Unified atomic mass unit
u
The unified atomic mass units is equal to 1/12 of the mass of an atom of the nuclide 12 C.

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Source: https://www.legislation.gov.uk/eudr/1980/181/annex/chapter/I/division/3 (the official version)
Page: https://openlegislation.uk/eu-directive-1980-181/annex/chapter-I/division-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.