<Table> SI base units <Tr> <Th> Name </Th> <Th> Symbol </Th> <Th> Measure </Th> <Th> Current ( 2005 ) formal definition </Th> <Th> Historical origin / justification </Th> <Th> Dimension symbol </Th> </Tr> <Tr> <Td> metre </Td> <Td> m </Td> <Td> length </Td> <Td> `` The metre is the length of the path travelled by light in vacuum during a time interval of 1 ⁄ 7008299792458000000 ♠ 299 792 458 of a second . '' 17th CGPM ( 1983 , Resolution 1 , CR , 97 ) </Td> <Td> 1 ⁄ 10,000,000 of the distance from the Earth 's equator to the North Pole measured on the circumference through Paris . </Td> <Td> </Td> </Tr> <Tr> <Td> kilogram </Td> <Td> kg </Td> <Td> mass </Td> <Td> `` The kilogram is the unit of mass ; it is equal to the mass of the international prototype of the kilogram . '' 3rd CGPM ( 1901 , CR , 70 ) </Td> <Td> The mass of one litre of water at the temperature of melting ice . A litre is one thousandth of a cubic metre . </Td> <Td> </Td> </Tr> <Tr> <Td> second </Td> <Td> s </Td> <Td> time </Td> <Td> `` The second is the duration of 7009919263177000000 ♠ 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom . '' 13th CGPM ( 1967 / 68 , Resolution 1 ; CR , 103 ) `` This definition refers to a caesium atom at rest at a temperature of 0 K . '' ( Added by CIPM in 1997 ) </Td> <Td> The day is divided in 24 hours , each hour divided in 60 minutes , each minute divided in 60 seconds . A second is 1 ⁄ ( 24 × 60 × 60 ) of the day . </Td> <Td> </Td> </Tr> <Tr> <Td> ampere </Td> <Td> </Td> <Td> electric current </Td> <Td> `` 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 metre apart in vacuum , would produce between these conductors a force equal to 2 × 10 newton per metre of length . '' 9th CGPM ( 1948 ) </Td> <Td> The original `` International Ampere '' was defined electrochemically as the current required to deposit 1.118 milligrams of silver per second from a solution of silver nitrate . Compared to the SI ampere , the difference is 0.015 % . </Td> <Td> </Td> </Tr> <Tr> <Td> kelvin </Td> <Td> </Td> <Td> thermodynamic temperature </Td> <Td> `` The kelvin , unit of thermodynamic temperature , is the fraction 1 ⁄ 7002273160000000000 ♠ 273.16 of the thermodynamic temperature of the triple point of water . '' 13th CGPM ( 1967 / 68 , Resolution 4 ; CR , 104 ) `` This definition refers to water having the isotopic composition defined exactly by the following amount of substance ratios : 0.000 155 76 mole of H per mole of H , 0.000 379 9 mole of O per mole of O , and 0.002 005 2 mole of O per mole of O . '' ( Added by CIPM in 2005 ) </Td> <Td> The Celsius scale : the Kelvin scale uses the degree Celsius for its unit increment , but is a thermodynamic scale ( 0 K is absolute zero ) . </Td> <Td> Θ </Td> </Tr> <Tr> <Td> mole </Td> <Td> mol </Td> <Td> amount of substance </Td> <Td> `` 1 . The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12 ; its symbol is ' mol ' . <P> 2 . When the mole is used , the elementary entities must be specified and may be atoms , molecules , ions , electrons , other particles , or specified groups of such particles . '' 14th CGPM ( 1971 , Resolution 3 ; CR , 78 ) `` In this definition , it is understood that unbound atoms of carbon 12 , at rest and in their ground state , are referred to . '' ( Added by CIPM in 1980 ) </P> </Td> <Td> Atomic weight or molecular weight divided by the molar mass constant , 1 g / mol . </Td> <Td> </Td> </Tr> <Tr> <Td> candela </Td> <Td> cd </Td> <Td> luminous intensity </Td> <Td> `` The candela is the luminous intensity , in a given direction , of a source that emits monochromatic radiation of frequency 7014540000000000000 ♠ 540 × 10 hertz and that has a radiant intensity in that direction of 1 / 683 watt per steradian . '' 16th
<Table> SI base units <Tr> <Th> Name </Th> <Th> Symbol </Th> <Th> Measure </Th> <Th> Current ( 2005 ) formal definition </Th> <Th> Historical origin / justification </Th> <Th> Dimension symbol </Th> </Tr> <Tr> <Td> metre </Td> <Td> m </Td> <Td> length </Td> <Td> `` The metre is the length of the path travelled by light in vacuum during a time interval of 1 ⁄ 7008299792458000000 ♠ 299 792 458 of a second . '' 17th CGPM ( 1983 , Resolution 1 , CR , 97 ) </Td> <Td> 1 ⁄ 10,000,000 of the distance from the Earth 's equator to the North Pole measured on the circumference through Paris . </Td> <Td> </Td> </Tr> <Tr> <Td> kilogram </Td> <Td> kg </Td> <Td> mass </Td> <Td> `` The kilogram is the unit of mass ; it is equal to the mass of the international prototype of the kilogram . '' 3rd CGPM ( 1901 , CR , 70 ) </Td> <Td> The mass of one litre of water at the temperature of melting ice . A litre is one thousandth of a cubic metre . </Td> <Td> </Td> </Tr> <Tr> <Td> second </Td> <Td> s </Td> <Td> time </Td> <Td> `` The second is the duration of 7009919263177000000 ♠ 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom . '' 13th CGPM ( 1967 / 68 , Resolution 1 ; CR , 103 ) `` This definition refers to a caesium atom at rest at a temperature of 0 K . '' ( Added by CIPM in 1997 ) </Td> <Td> The day is divided in 24 hours , each hour divided in 60 minutes , each minute divided in 60 seconds . A second is 1 ⁄ ( 24 × 60 × 60 ) of the day . </Td> <Td> </Td> </Tr> <Tr> <Td> ampere </Td> <Td> </Td> <Td> electric current </Td> <Td> `` 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 metre apart in vacuum , would produce between these conductors a force equal to 2 × 10 newton per metre of length . '' 9th CGPM ( 1948 ) </Td> <Td> The original `` International Ampere '' was defined electrochemically as the current required to deposit 1.118 milligrams of silver per second from a solution of silver nitrate . Compared to the SI ampere , the difference is 0.015 % . </Td> <Td> </Td> </Tr> <Tr> <Td> kelvin </Td> <Td> </Td> <Td> thermodynamic temperature </Td> <Td> `` The kelvin , unit of thermodynamic temperature , is the fraction 1 ⁄ 7002273160000000000 ♠ 273.16 of the thermodynamic temperature of the triple point of water . '' 13th CGPM ( 1967 / 68 , Resolution 4 ; CR , 104 ) `` This definition refers to water having the isotopic composition defined exactly by the following amount of substance ratios : 0.000 155 76 mole of H per mole of H , 0.000 379 9 mole of O per mole of O , and 0.002 005 2 mole of O per mole of O . '' ( Added by CIPM in 2005 ) </Td> <Td> The Celsius scale : the Kelvin scale uses the degree Celsius for its unit increment , but is a thermodynamic scale ( 0 K is absolute zero ) . </Td> <Td> Θ </Td> </Tr> <Tr> <Td> mole </Td> <Td> mol </Td> <Td> amount of substance </Td> <Td> `` 1 . The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12 ; its symbol is ' mol ' . <P> 2 . When the mole is used , the elementary entities must be specified and may be atoms , molecules , ions , electrons , other particles , or specified groups of such particles . '' 14th CGPM ( 1971 , Resolution 3 ; CR , 78 ) `` In this definition , it is understood that unbound atoms of carbon 12 , at rest and in their ground state , are referred to . '' ( Added by CIPM in 1980 ) </P> </Td> <Td> Atomic weight or molecular weight divided by the molar mass constant , 1 g / mol . </Td> <Td> </Td> </Tr> <Tr> <Td> candela </Td> <Td> cd </Td> <Td> luminous intensity </Td> <Td> `` The candela is the luminous intensity , in a given direction , of a source that emits monochromatic radiation of frequency 7014540000000000000 ♠ 540 × 10 hertz and that has a radiant intensity in that direction of 1 / 683 watt per steradian . '' 16th
what is the standard base unit for length
what is the standard base unit for length
metre
metre