Quantity; unit (symbol)
Amount of substance; mole (mol)
1 mole (mol) = the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12.
Electric current; ampere (A)
1 ampere (A) = that constant which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross section, and placed 1 metre apart in a vacuum, would produce between those conductors a force equal to 2 x
10-7 newton metre of length.
Length; metre (m)
1 metre (m) = the length of light travelled by light in a vacuum during a time interval of 1/299 792 458 of a second.
Luminous intensity; candela (cd)
1 candela (cd) = the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency of 540 x 1012 hertz and that has a radiant intensity in that direction of (1/683) watt per steradian.
Mass; kilogram (kg)
1 kilogram (kg) = the mass of the international prototype of the kilogram.
Thermodynamic temperature; kelvin (K)
1 Kelvin (K) = the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.
Time; second (s)
1 second = 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 when exited.