1. The International System of Units - international system (SI)
The coordinated number of physical quantity measurement units having a description of reference basic physical quantities as well as mandatory names and designations of derived quantity units accepted by General Conference of Weights and Measures in 1960.
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Electric current intensity | | | | |
Thermodynamic temperature (Kelvin) | | | | |
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Derived units of space and time |
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| | radian per second squared | | |
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Continued
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Derived units of mechanical quantities |
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Amount of movement (pulse) | | kilogram-meter per second | | |
Angular momentum (angular impulse) | | kilogram-meter squared per second | | |
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Force moment, moment of couple | | | | |
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Derived units of electric and magnetic quantities |
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Quantity of electricity, electric charge | | | | |
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Electric voltage, electric potential, electromotive intensity | | | | |
Continued
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Absolute dielectric constant | | | | |
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Magnetic moment of electrical current, magnetic dipole moment | | | | |
Derived units of heat quantities |
Quantity of heat, thermodynamic potential | | | | |
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| | joule per kilogram-kelvin | | |
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Heat-exchange coefficient, heat-transfer coefficient | | watt per square meter-kelvin | | |
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Derived units of light quantities |
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End of table
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| | candella per square meter | | |
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Derived units of quantities relating to ionizing radiation |
Ionizing radiation energy | | | | |
Flux of ionizing radiation energy | | | | |
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| | second to the minus first | | |
Decimal prefix to unit names
Measurement standards of basic physical quantity units SI
Meter. Length unit in SI; it is equal to a distance between axes of two lines laid on the platinum-iridium bar stored at the International Bureau of Weights and Measures at 0 °С and standard pressure. As defined, the meter is equal to
1650763.73 wavelength of radiation of Krypton-86 atom when transitioning from 2р10 level to 5d5 level in vacuum or is equal to the distance covered by light in vacuum during 1/2997922458 sec.
Kilogram. Mass unit in SI; it is equal to the mass of the international measurement standard (prototype) made of platinum-iridium alloy stored at the International Bureau of Weights and Measures. Mass of this standard is by 0.000028 kg more than mass of one cubic decimeter of chemically pure water at the temperature of its maximum density (+3.98 °С).
Second. Time unit in SI; it is equal, by atomic clock ("atomic second"), to 9192631770 periods of the radiation corresponding to the energy transition between two levels of the ground state hyperfine structure of caesium-133 atom and by ephemerid determination - 1/315569259747 part of tropical year (relative distinction between the two is ≈ 2?10-9). Second, equal to 1/86400 part of a star or average solar days, is equal to 0.99726966 atomic seconds.
Ampere. Current strength unit in SI system; it is equal to the strength of the direct current, passing which through two parallel straight conductors of infinite length and negligibly small section area, located in vacuum at a distance of 1 meter between the two, induces in the conductor section of 1 meter in length and interacting force equal to 2 ? 10-7 N. Magnetomotive force is measured in amperes too.