249 Table 1. Base Units Note (1) The elementary particles here must be atoms, molecules, ions, electrons or other particles. Table 2. Supplementary Units (5) Derived Units The supplementary units algebraically expressed using mathematical symbols such as plus, minus, etc. The SI derived units with special names and symbols are given in Table 3. 1. International System of Units(SI)and Usage. 1-1. Scope of Application This standard specifies how to use the International System of Units(SI) and other international unitary systems, as well as units used in correlation with units from international systems, and other units which may be used. 1-2. Terms and Definitions Terminology used in this specification and definitions thereof are as follows. (1) International System of Units(SI) Coherent system of units adopted and recommended by the International Committee on Weights and Measures. It contains base units and supplementary units, units derived from them and their integral exponents to the 10th power. (2) SI Unit Generic term used to describe base units, supplementary units or derived units of the International System of Units(SI). (3) Base Unit Those units are given in Table 1. (4) Supplementary Units Those supplementary units are given in Table 2. Examples of SI Derived Units Expressed in Terms of Base Units Table 3 SI Derived Units with Special Names and Symbols Base Quantity Unit Symbol Definition Length Meter m A meter is the length of the path traveled by light in a vacuum during a time interval of 1 299 792 458 of a second. Mass Kilogram kg A kilogram is a unit of mass(neither weight nor force), it is equal to the mass of the international prototype of the kilogram. Time Second s A second is the duration of 9 192 631 770 periods of radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. Current Ampere A An 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 a vacuum, would produce between these conductors a force equal to 2×10−7 Newton per meter of length. Thermodynamic Temperature Kelvin K Kelvin, a unit of thermodynamic temperature, is the fraction 1 273.16 of the thermodynamic temperature of the triple point of water. Amount of Substance Mole mol A mole is the amount of substance of a system that contains as many elementary particles(1) or aggregation of elementary particles as there are atoms in 0.012 kilogram of carbon 12 and when the mole is used, the elementary particles must be specified. Luminance Intensity Candela cd A candela is 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. Base Quantity Unit Symbol Definition Plane Angle Radian rad A radian is the plane angle between two radii of a circle that cuts off an arc on the circumference equal in length to the radius. Solid Angle Steradian sr A steradian is the solid angle which, having its vertex in the center of a sphere, cuts off an area of the surface of the sphere equal to that of a square with sides equal in length to the radius of the sphere. Base Quantity Base Quantity Name Symbol Area Square Meter m2 Volume Cubic Meter m3 Velocity Meter/Second m/s Acceleration Meter/Second2 m/s2 Wave Number Every Meter m−1 Density Kilogram Every Cubic Meter kg/m3 Current Density Ampere Every Square Meter A/m2 Magnetic Field Strength Ampere Every Meter A/m Concentration (of Substance) Mole Every Cubic Meter mol/m3 Specific Volume Cubic Meter Every Kilogram m3/kg Luminance Candela Every Square Meter cd/m2 Base Quantity Base Quantity Expression in Terms of Base Units or Supplementary Units, Supplementary Units or Other SI Units Name Symbol Frequency Hertz Hz 1 Hz =1 s−1 Force Newton N 1 N =1 kg·m/s2 Pressure, Stress Pascal Pa 1 Pa =1 N/m2 Energy, Work, Heat Quantity Joule J 1 J =1 N·m Work Rate, Process Rate, Power, Electric Power Watt W 1 W =1 J/s Electric Charge, Quantity of Electricity Coulomb C 1 C =1 A·s Electric Potential, Potential Difference, Voltage, Electromotive Force Volts V 1 V =1 J/C Electrostatic Capacity, Capacitance Farad F 1 F =1 C/V Electric Resistance Ohm Ω 1 Ω =1 V/A Conductance Siemens S 1 S =1 Ω−1 Magnetic Flux Weber Wb 1 Wb =1 V·s Magnetic Flux Density Tesla T 1 T =1 Wb/m2 Inductance Henry H 1 H =1 Wb/A Celsius Temperature Degree Celsius ˚C 1 t˚C =(t+273.15)k Luminous Flux Lumen lm 1 lm =1 cd·sr Illuminance Lux lx 1 lx =1 lm/m2 Radioactivity Becquerel Bq 1 Bq =1 s−1 Absorbed Dose Gray Gy 1 Gy =1 J/kg Dose Equivalent Sievert Sv 1 Sv =1 J/kg GeneralTechnical Information SI (International System of Units)
RkJQdWJsaXNoZXIy MTc2MTk0OA==