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Version Superseded: 13/06/2020
EU Directives are published on this site to aid cross referencing from UK legislation. Since IP completion day (31 December 2020 11.00 p.m.) no amendments have been applied to this version.
| Quantity | Unit | |
|---|---|---|
| Name | Symbol | |
| Length | metre | m |
| Mass | kilogram | kg |
| Time | second | s |
| Electric current | ampere | A |
| Thermodynamic temperature | kelvin | K |
| Amount of substance | mole | mol |
| Luminous intensity | candela | cd |
A metre is the length of the path travelled in a vacuum by light during 1/ 299 792 458 seconds.
(Seventeenth CGPM (1983), Resolution 1).]
Textual Amendments
The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.
(Third CGPM (1901), page 70 of the conference report).
The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.
(Thirteenth CGPM (1967), resolution 1).
The ampere is that constant current, which if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one metre apart in vacuum, would produce between those conductors a force equal to 2 × 10 -7 newton per metre of length.
(CIPM (1946), resolution 2, approved by the ninth CGPM (1948)).
The kelvin, unit of thermodynamic temperature, is the fraction 1/273,16 of the thermodynamic temperature of the triple point of water.
This definition refers to water having the isotopic composition defined by the following amount-of-substance ratios: 0,00015576 mole of 2 H per mole of 1 H, 0,0003799 mole of 17 O per mole of 16 O and 0,0020052 mole of 18 O per mole of 16 O.
(Thirteenth CGPM (1967), resolution 4 and Twenty-third CGPM (2007), resolution 10)]
Textual Amendments
The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0·012 kilogram of carbon 12.
When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.
(Fourteenth CGPM (1971), resolution 3).
The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency of 540 × 10 12 hertz and that has a radiant intensity in that direction of (1/683) watt per steradian.
(Sixteenth CGPM (1979), resolution 3).
| Quantity | Unit | |
|---|---|---|
| Name | Symbol | |
| Celsius temperature | degree Celsius | °C |
[F3Celsius temperature [X2t] is defined as the difference [X2t = T - T 0] between the two thermodynamic temperatures [X2T] and [X2T 0 where T 0] = 273,15 K. An interval or difference of temperature may be expressed either in kelvins or in degrees Celsius. The unit ‘ degree Celsius ’ is equal to the unit ‘ kelvin ’ .] ]
Editorial Information
X2 Substituted by Corrigendum to Directive 1999/103/EC of the European Parliament and of the Council of 24 January 2000 amending Council Directive 80/181/EEC on the approximation of the laws of the Member States relating to units of measurement (Official Journal of the European Communities L 34 of 9 February 2000).
Textual Amendments
Editorial Information
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