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A base quantity is chosen and arbitrarily defined, rather than being derived from a combination of other physical quantities. The 7 base quantities are:
|PHYSICAL QUANTITY||BASE SI UNIT|
|Mass (m)||Kilogram (Kg)|
|Length (ll)||Metre (m)|
|Time (t)||Second (s)|
|Current (II)||Ampere (A)|
|Temperature (T)||Kelvin (K)|
|Amount of sub. (n)||Molar (mol)|
|Luminous Intensity (L)||Candela (cd|
The SI base units and their physical quantities are the metre for measurement of length, the kilogram for mass, the second for time, the ampere for electric current, the kelvin for temperature, the candela for luminous intensity, and the mole for amount of substance.
Derived units are units which may be expressed in terms of base units by means of mathematical symbols of multiplication and division.
For example, the SI derived unit of area is the square metre (m2), and the SI derived unit of density is the kilogram per cubic metre (kg/m3 or kg m-3).
The names of SI units are written in lowercase.