SI units
SI units (Système International d'Unites) Internationally agreed system of units, derived from the mks (metre, kilogram, and second) system. SI units are now used for many scientific purposes, and have replaced the fps (foot, pound, and second) and cgs (centimetre, gram, and second) systems. The seven basic units are: the metre (m) for length, kilogram (kg) for mass, second (s) for time, ampere (A) for electrical current, Kelvin (K) for temperature, mole (mol) for amount of substance, and candela (cd) for luminous intensity.
Measurement | Unit | Symbol |
|---|---|---|
Basic units | ||
Length | metre | m |
Mass | kilogram | kg |
Time | second | s |
Electric current | ampere | A |
Thermodynamic temperature | kelvin | K |
Amount of substance | mole | mol |
Luminous intensity | candela | cd |
Supplementary units | ||
Plane angle | radian | rad |
Solid angle | steradian | sr |
Derived units | ||
Frequency | hertz | Hz |
Force | newton | N |
Pressure, stress | pascal | Pa |
Work (energy, heat) | joule | J |
Power | watt | W |
coulomb | C | |
Electromotive force | volt | V |
Electric resistance | ohm | 1/2 |
Electric conductance | siemens | S |
Electric capacitance | farad | F |
Inductance | henry | H |
Magnetic flux | weber | Wb |
Magnetic flux density | tesla | T |
Illuminance | lux | lx |
Luminous flux | lumen | lm |
röntgen | r | |
Radiation activity | becquerel | Bq |
Radiation absorbed dose | gray | Gy |
Radiation dose equivalent | sievert | Sv |
Celsius temperature | °Celsius | °C |
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SI units
