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base SI unit
subject			fact

base SI unit	has definition a unit assumed to be mutually independent from which all other units are derived
	is a kind of SI unit
SI unit	is an acronym for Syteme Internationale
unit	has historical origin
	represents

Kinds of base SI unit :

• ampere (6 facts) (A) - Unit of electric current. "The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 × 10^-7 newton per meter of length" CIPM 1946, Resolution 2, approved by the 9th CGPM 1948). A current of 1 A is equivalent to the passage along the filament of a light bulb of about 6 × 10¹⁸ electronic charges per second., constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 meter apart in vacuum, would produce between these conductors a force equal to 2 × 10^-7 newton per meter of length
• candela (8 facts) (cd) - The SI unit of luminous intensity, defined as "the luminous intensity, in the perpendicular direction, of a surface of 1/600000 square meter of a blackbody at the temperature of freezing platinum under a pressure of 101325 newtons per square meter.", the luminous intensity in a given direction, of a source that emits monochromatic radiation of frequency 540 × 10¹² hertz and that has a radiant intensity in that direction of 1/683 watt per steradian
• Kelvin (12 facts) (K, absolute) - The fraction 1/273.16 of the thermodynamic temperature of the triple point of water (the point at which the solid, liquid and gaseous phase of pure water are in equilibrium). Absolute zero corresponds to zero energy. Represents the same temperature interval as those on the Celsius scale., Unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water
• kilogram (6 facts) (kg) - Unit of mass (not of weight or of force). Kilogram is equal to the mass of 1.000028 cubic decimeters of water at the temperature of its maximum density., Unit of mass equal to the international prototype of the kilogram
• meter (9 facts) (m) - A unit of length. The meter is the length equal to 1650763.73 wavelengths in vacuum of the radiation corresponding to the transition between the levels 2p₁₀ and 5d₅ of the Krypton-86 atom., length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second
• mole (8 facts) (mol) - The SI unit of the amount of substance, defined as the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilograms of carbon 12. One mole, which is equal to gram multiplied by the molecular weight, contains 6.02 × 10²³ molecules (see Avogadro's number). In general, 1 mole of any gas occupies a volume of 22.4 liters., amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12
• second (6 facts) (s) - A unit of time defined as the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom. In 1967 the General Conference of Weights and Measures (CGPM) adopted this as the tentative definition of the second in SI units, replacing the ephemeris second, which remains in the IAU system of astronomical constants., duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom