Table 1.9

The defining constants of the SI.

Defining constantSymbolNumerical valueUnit
the unperturbed ground state hyperfine transition frequency of the caesium 133 atom ΔνCs 9192631770 Hz 
the speed of light in vacuum c 299792458 m s−1 
the Planck constant h 6.62607015  ×  10−34 J s 
the elementary charge e 1.602176634  ×  10−19 C 
the Boltzmann constant k 1.380649  ×  10−23 J K−1 
the Avogadro constant NA 6.02214076  ×  1023 mol−1 
the luminous efficacy of a defined visible radiation Kcd 683 lm W−1 
Defining constantSymbolNumerical valueUnit
the unperturbed ground state hyperfine transition frequency of the caesium 133 atom ΔνCs 9192631770 Hz 
the speed of light in vacuum c 299792458 m s−1 
the Planck constant h 6.62607015  ×  10−34 J s 
the elementary charge e 1.602176634  ×  10−19 C 
the Boltzmann constant k 1.380649  ×  10−23 J K−1 
the Avogadro constant NA 6.02214076  ×  1023 mol−1 
the luminous efficacy of a defined visible radiation Kcd 683 lm W−1 
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