SI REFERENCE POINT
Version: 1.0 Beta, last update: 2024-02-14

Defining constants

Lists the defining constants of the SI.

The knowledge base can be downloaded from this link: constants.ttl
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Constant Symbol Numerical value SI Unit Last Update PID (Constant)
Avogadro constant ${N_{\rm{A}}}$ 6.022 140 76 x 10²³ $$\text{mol}^{-1}\ \ $$ 2019-05-20
Boltzmann constant ${k}$ 1.380 649 x 10⁻²³ $$\text{J}^{}\ \ \text{K}^{-1}\ \ $$ 2019-05-20
Planck constant ${h}$ 6.626 070 15 x 10⁻³⁴ $$\text{J}^{}\ \ \text{s}^{}\ \ $$ 2019-05-20
elementary charge ${e}$ 1.602 176 634 x 10⁻¹⁹ $$\text{C}^{}$$ 2019-05-20
hyperfine transition frequency of Cs-133 $\Delta\nu_{\rm{Cs}}$ 9 192 631 770 $$\text{Hz}^{}$$ 1967-10-13
luminous efficacy ${K_{\rm{cd}}}$ 683 $$\text{lm}^{}\ \ \text{W}^{-1}\ \ $$ 1979-10-11
speed of light $c$ 299 792 458 $$\text{m}^{}\ \ \text{s}^{-1}\ \ $$ 1975-06-03