Unit Kilogram Unit Symbol kg Base Measure Mass Physical Constant Plancks Constant (h) - relationship between a photons energy and frequency Definition Defined by taking Plancks constant (h) to be a fixed numerical value of 6.62607015×10−34...
Unit Ampere Unit Symbol A Base Measure Electric Current Physical Constant Elementary charge (e) - the charge of a single proton Definition Defined by taking the elementary charge e to be a fixed numerical value of 1.602176634×10...
Unit Mole Unit Symbol mol Base Measure Amount of Substance Physical Constant Avagadro's constant - a value of 6.02214076 × 1023 Definition The amount of substance that contains the same number of particles as there are atoms in 0.012 kg (12 g) of carbon-12,...
Unit Metre Unit Symbol m Base Measure Length Physical Constant Speed of light (c) Definition The length of the path travelled by light in a vacuum during a time interval of 1/299,792,458 of a...
Unit Second Unit Symbol s Base Measure Time Physical Constant Hyperfine transition frequency of caesium (ΔνCs) Definition The time taken by 9,192,631,770 oscillations of the light emitted by a caesium-133...
