UCUM derived unit
UCUM derived units are units of measurement derived from the seven base units specified by the Unified Code for Units of Measure (UCUM).[dubious ] They can be expressed as a product of one or more of the base units, possibly scaled by an appropriate power of exponentiation.
The UCUM has special names for 20 of these derived units[disputed ] (for example, hertz, the UCUM unit of measurement of frequency), but the rest merely reflect their derivation: for example, the square metre (m2), the UCUM derived unit of area; and the gram per cubic metre (g/m3 or g m−3), the UCUM derived unit of density.
The names of UCUM derived units, when written in full, are in lowercase. However, the symbols for units named after persons are written with an uppercase initial letter. For example, the symbol for hertz is "Hz"; but the symbol for metre is "m".
Derived units with special names
The Unified Code for units of measure assigns special names to 20 derived units.[disputed ] There are many SI derived units like the Newton that are defined in terms of the kilogram, the SI unit of mass. But the UCUM unit of mass is the gram, not the kilogram. So there are many units in the UCUM with prefixes like the millinewton.
|Name||Symbol||Quantity||Equivalents||UCUM base unit|
|steradian||sr[n 1]||solid angle||rad2||rad2|
|millijoule||mJ||energy, work, heat||mN⋅m
|milliwatt||mW||power, radiant flux||mJ/s
|ampere||A[n 2]||electric current||C/s
|millivolt||mV||voltage, electrical potential difference, electromotive force||mW/A
|milliohm||mΩ||electrical resistance, impedance, reactance||1/kS
|millitesla||mT||magnetic induction, magnetic flux density||mV⋅s/m2
|degree Celsius||°C||temperature relative to 273.15 K||K||K|
|becquerel||Bq||radioactivity (decays per unit time)||1/s||s−1|
|gray||Gy||absorbed dose (of ionizing radiation)||mJ/g||m2⋅s−2|
|sievert||Sv||equivalent dose (of ionizing radiation)||mJ/g||m2⋅s−2|
Examples of derived quantities and units
Template:UCUM other units
Other units used with UCUM
Some other units such as the hour, litre, tonne, bar and electronvolt are not UCUM units, but are widely used in conjunction with UCUM units.
- International Vocabulary of Metrology
- Metric prefix
- Metric system
- Planck units
- I. Mills, Tomislav Cvitas, Klaus Homann, Nikola Kallay, IUPAC (June 1993). Quantities, Units and Symbols in Physical Chemistry (2nd ed.). Blackwell Science Inc. p. 72.CS1 maint: Multiple names: authors list (link) Search this book on
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