SI基本单位(国外英文资料).docVIP

SI基本单位(国外英文资料) SI basic unit The seven units under the international system of units are based on the following units, and these seven units are called the basic units of SI. Molar amount of mol name unit name unit symbol length m m kg kg seconds s quality A ampere Kelvin thermodynamic temperature K material intensity candela CD The definition of the basic unit of SI M: length of path passed in a vacuum (1/299, 792458) s time interval. [Seventeenth International Conference on Metrology (1983)] Kilogram: the quality of an international kilogram of raw materials. [First International Conference on Metrology (1889) and Third International Conference on Metrology (1901)] The duration of the 9192631770 cycles corresponding to the transition between the two hyperfine levels of the atomic -133 ground state. [Thirteenth International Congress on Metrology (1967), resolution 1] A: in a vacuum, infinite two sectional area of negligible distance 1 m parallel circle straight wire pass with equal constant current, if the interaction between wires in each meter length is 2 * 10-7 N, the current in each wire is 1 A. [International Commission on measurement (1946) resolution 2. Approval of the Ninth International Conference on Metrology (1948) Kelvin: the thermodynamic temperature of the three-phase point of water is 1/273.16. [Thirteenth International Congress on Metrology (1967), resolution 4] Moore: is a system of amount of substance, the basic unit contained in the system (a specific combination of atoms, molecules, ions, electrons and other particles, and these particles) and 0.012 kg carbon atom number equal to -12. [Fourteenth International Congress on Metrology (1971), resolution 3] Candela: the luminous intensity of a light source in a given direction. The light source emits monochromatic radiation with a frequency of 540 * 1012 Hz, and the radiation intensity in this direction is (1/683) W/sr. [Sixteenth International Congress on Metrology (1979), resolution 3] SI export