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SI Units

The international system of units known as the SI units is based on the seven basic units: Mass, Length, Time, Electric current, Temperature, Amount of substance and Luminous intensity.

The basic seven quantities from which other units are derived are tabulated below:

Basic quantity	Name	Symbol
Mass	kilogram	kg
Length	metre	m
Time	second	s
Electric current	Ampere	A
Temperature	Kelvin	K
Amount of substance	mole	mol
Luminous intensity	candela	cd

The radian and steradian may also be treated as basic units.

These are multiplications and divisions of the basic units to form derived units. Some of these derived units are listed below along with their derivation in terms of basic units:

Derived quantity	Name	Symbol	Basic Unit Derivation
Capacitance	farad	F	kg^-1m^-2s⁴A²
Charge	coulomb	C	As
Conductance	siemens	S	kg^-1m^-2s³A²
Electromotive Force	volt	V	kgm²s^-3A^-1
Energy	joule	J	kgm²s^-2
Force	newton	N	kgms^-2
Frequency	hertz	Hz	s^-1
Inductance	henry	H	kgm²s^-2A^-2
Magnetic Flux	weber	Wb	kgm²s^-2A^-1
Magnetic Flux Density	tesla	T	kgs^-2A^-1
Power	watt	W	kgm²s^-3
Pressure	pascal	Pa	kgm^-1s^-2
Resistance	ohm	Ω	kgm²s^-3A^-2

Weblinks:

International Standards Organisation Responsible for the world-wide publication of standards.
National Institute of Standards and Technology USA based organisation.