One of the seven units of measurement that define the metric system
The seven SI base units
Symbol
Name
Base quantity
s
second
time
m
metre
length
kg
kilogram
mass
A
ampere
electric current
K
kelvin
thermodynamic temperature
mol
mole
amount of substance
cd
candela
luminous intensity
The SI base units are the standard units of measurement defined by the International System of Units (SI) for the seven base quantities of what is now known as the International System of Quantities: they are notably a basic set from which all other SI units can be derived. The units and their physical quantities are the second for time, the metre (sometimes spelled meter) for length or distance, the kilogram for mass, the ampere for electric current, the kelvin for thermodynamic temperature, the mole for amount of substance, and the candela for luminous intensity. The SI base units are a fundamental part of modern metrology, and thus part of the foundation of modern science and technology.
The SI base units form a set of mutually independent dimensions as required by dimensional analysis commonly employed in science and technology. [citation needed]
The names and symbols of SI base units are written in lowercase, except the symbols of those named after a person, which are written with an initial capital letter. For example, the metre has the symbol m, but the kelvin has symbol K, because it is named after Lord Kelvin and the ampere with symbol A is named after André-Marie Ampère.
The SIbaseunits are the standard units of measurement defined by the International System of Units (SI) for the seven base quantities of what is now...
In 2019, four of the seven SIbaseunits specified in the International System of Quantities were redefined in terms of natural physical constants, rather...
SI derived units are units of measurement derived from the seven SIbaseunits specified by the International System of Units (SI). They can be expressed...
commerce. The SI comprises a coherent system of units of measurement starting with seven baseunits, which are the second (symbol s, the unit of time), metre...
System of Units (SI), equal to one thousandth of a metre, which is the SIbaseunit of length. Therefore, there are one thousand millimetres in a metre....
A baseunit of measurement (also referred to as a baseunit or fundamental unit) is a unit of measurement adopted for a base quantity. A base quantity...
Since its introduction in 1960, the baseunits for the International system of units, known as SI, have changed several times. Tables in this article...
examples are the units of the International System of Units (SI). By extension they include units of electromagnetism from the CGS and SIunits systems, and...
rad = 1 and expressed in terms of the SIbaseunit metre (m) as rad = m/m. Angles without explicitly specified units are generally assumed to be measured...
physicist Hans Christian Ørsted. As of the 2019 redefinition of the SIbaseunits, the ampere is defined by fixing the elementary charge e to be exactly...
science and in commerce. Two of the baseSIunits and 17 of the derived units are named after scientists. 28 non-SIunits are named after scientists. By this...
a base quantity is a single upper case letter in roman (upright) sans-serif type."). The associated quantity symbol, the SIunit name and SIunit symbol...
The kilogram (also kilogramme) is the baseunit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure...
1×10−12 m, or one trillionth (1/1000000000000) of a metre, which is the SIbaseunit of length. The picometre is one thousand femtometres, one thousandth...
expressing duration. The base unit of time in the International System of Units (SI), and by extension most of the Western world, is the second, defined as...
use with the International System of Units (SI). In addition to those listed in the everyday-use table, the SI includes standardised prefixes for 1015...
is named after the English physicist Michael Faraday (1791–1867). In SIbaseunits 1 F = 1 kg−1⋅m−2⋅s4⋅A2. The capacitance of a capacitor is one farad...
(/tʌn/ or /tɒn/; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SIunit accepted for use with SI. It is also referred to as a metric...
practical work as early as 1861. Following the 2019 redefinition of the SIbaseunits, in which the ampere and the kilogram were redefined in terms of fundamental...
second. The hertz is an SI derived unit whose expression in terms of SIbaseunits is s−1, meaning that one hertz is the reciprocal of one second. It is...
/kænˈdiːlə/; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by...
watt of power between those points. It can be expressed in terms of SIbaseunits (m, kg, s, and A) as V = power electric current = W A = kg ⋅ m 2 ⋅ s...
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