SI Base Unit
The International System of Units (SI) defines seven units of measure as a basic set from which all other SI units are derived. These SI base units and their physical quantities are:
- metre for length (US English: meter)
- kilogram for mass (note: not the gram)
- second for time
- ampere for electric current
- kelvin for temperature
- candela for luminous intensity
- mole for the amount of substance.
The SI base quantities form a set of mutually independent dimensions as required by dimensional analysis commonly employed in science and technology. However, in a given realization of these units they may well be interdependent, i.e. defined in terms of each other.
The names of SI units are written in lowercase characters (the 'degree Celsius' meets this rule, as 'degree' is the unit, and 'Celsius' is a modifier). The symbols of units are written in lowercase (e.g. metre has the symbol m), except that symbols for units named after persons are written with an initial capital letter (e.g., the hertz has the uppercase symbol Hz).
Many other units, such as the litre (US English: liter), are formally not part of the SI, but are accepted for use with SI.
Read more about SI Base Unit: The Seven SI Base Units, Future Redefinitions
Famous quotes containing the words base and/or unit:
“Time, force, and death
Do to this body what extremes you can,
But the strong base and building of my love
Is as the very centre of the earth,
Drawing all things to it.”
—William Shakespeare (1564–1616)
“During the Suffragette revolt of 1913 I ... [urged] that what was needed was not the vote, but a constitutional amendment enacting that all representative bodies shall consist of women and men in equal numbers, whether elected or nominated or coopted or registered or picked up in the street like a coroner’s jury. In the case of elected bodies the only way of effecting this is by the Coupled Vote. The representative unit must not be a man or a woman but a man and a woman.”
—George Bernard Shaw (1856–1950)