Search facility:  
BIPM Home | Site map | Metrologia | KCDB | JCTLM-DB | Contact us  
   
What changes are proposed?
Version française
Summary
Why change the SI?
What changes are proposed?
The "explicit-constant" formulation
What is a mise en pratique?
When might the changes take place?
What is the BIPM contributing?
Discussions on the New SI in the Consultative Committees
Discussion in the scientific literature
FAQs, Frequently Asked Questions about the New SI
Key documents
Discussion Meeting
Related articles
Resolution 1 (CGPM 2011)
Direct access

Resolution 1 adopted by the CGPM in 2011 takes note of the CIPM's intention to propose a future revision of the SI.

It explains that the intention is to propose a revision such that:

the International System of Units, the SI, will be the system of units in which:
  • the ground state hyperfine splitting frequency of the caesium 133 atom capital Deltanu(133Cs)hfs is exactly 9 192 631 770 hertz,


  • the speed of light in vacuum c is exactly 299 792 458 metre per second,


  • the Planck constant h is exactly 6.626 06X x 10–34 joule second,


  • the elementary charge e is exactly 1.602 17X x 10–19 coulomb,


  • the Boltzmann constant k is exactly 1.380 6X x 10–23 joule per kelvin,


  • the Avogadro constant NA is exactly 6.022 14X x 1023 reciprocal mole,


  • the luminous efficacy Kcd of monochromatic radiation of frequency 540 x 1012 Hz is exactly 683 lumen per watt,
where

(i) the hertz, joule, coulomb, lumen, and watt, with unit symbols Hz, J, C, lm, and W, respectively, are related to the units second, metre, kilogram, ampere, kelvin, mole, and candela, with unit symbols s, m, kg, A, K, mol, and cd, respectively, according to Hz = s–1, J = m2 kg s–2, C = s A, lm = cd m2 m–2 = cd sr, and W = m2 kg s–3,

(ii) the symbol X represents one or more additional digits to be added to the numerical values of h, e, k, and NA, using values based on the most recent CODATA adjustment

Resolution 1 also presents the intention to express the definitions of all the base units using a uniform "explicit-constant" formulation.

For full details the reader is referred to the formal text of the Resolution.



Related articles

Resolution 1 (CGPM 2011)