View source for S.I. Units

The modern metric system is the [https://en.wikipedia.org/wiki/International_System_of_Units '''International System of Units'''] ''(French: Système International d'Unités, SI)''.  The system was published in 1960 and was based on the metre-kilogram-second system of units (MKS). There are now internationally agreed units covering all aspects of technology together with a set of prefixes which serve as multipliers or fractions of them. The preferred prefixes multiply or divide the unit names by 1000 ''(or 10<sup>-3</sup>)'' thus, 10mm is preferred to a centimetre, especially in construction and engineering.

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<span style="color: green">'''Note:'''
[http://en.wikipedia.org/wiki/List_of_scientific_units_named_after_people '''''Units named after people'''''] use capital letters for the letter symbol - but not for the unit name itself.
</span>
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__TOC__


=====Measurement of Length=====
{|
|-
| colspan="5"|[https://en.wikipedia.org/wiki/Metre '''Metre''']
|-
| '''Prefix Name'''
| '''Symbol'''
| '''10<sup>n</sup>'''
| '''Decimal'''
| '''Description'''
|-
| kilometre
| km
| 10<sup>3</sup>
| 1000
| A thousand metres
|-
| metre
| m
| 10<sup>0</sup>
| 1
| A metre
|-
| centimetre
| cm
| 10<sup>-2</sup>
| 0.01
| A hundredth of a metre
|-
| millimetre
| mm
| 10<sup>-3</sup>
| 0.001
| A thousandth of a metre
|-
| micrometre
| μm
| 10<sup>-6</sup>
| 0.000001
| A millionthth of a metre
|}
=====Units used in Electronics=====
{|
|-
| colspan="5"|[https://en.wikipedia.org/wiki/Ohm '''Ohms (resistance)'''] - named after [https://en.wikipedia.org/wiki/Georg_Ohm '''Georg Simon Ohm''']
|-
| '''Prefix Name'''
| '''Symbol'''
| '''10<sup>n</sup>'''
| '''Decimal'''
| '''Description'''
|-
| mega-ohm
| MΩ
| 10<sup>6</sup>
| 1000000
| A million ohms
|-
| kilo-ohm
| kΩ ''(or K)''
| 10<sup>3</sup>
| 1000
| A thousand ohms
|-
| ohm
| Ω ''(or R)''
| 10<sup>0</sup>
| 1
| An ohm
|-
| colspan="5"|<span style="color: green">'''Note:'''
The unit or its prefix may be used to replace a decimal point - e.g. 2.2mega-ohm = 2M2; 2.2kilo-ohm = 2K2; and 2.2ohm = 2R2.
</span>
|-
| colspan="5"|[https://en.wikipedia.org/wiki/Ampere '''Ampere (electric current)'''] - named after [https://en.wikipedia.org/wiki/Andr%C3%A9-Marie_Amp%C3%A8re ''André-Marie Ampère''']
|-
| '''Prefix Name'''
| '''Symbol'''
| '''10<sup>n</sup>'''
| '''Decimal'''
| '''Description'''
|-
| ampere
| A
| 10<sup>0</sup>
| 1
| Amp
|-
| milli-amp
| mA
| 10<sup>-3</sup>
| 0.001
| A thousandth
|-
| colspan="5"|[https://en.wikipedia.org/wiki/Farad '''Farads (electric capacitance)'''] - named after [https://en.wikipedia.org/wiki/Michael_Faraday '''Michael Faraday''']
|-
| '''Prefix Name'''
| '''Symbol'''
| '''10<sup>n</sup>'''
| '''Decimal'''
| '''Description'''
|-
| farad
| F
| 10<sup>0</sup>
| 1
| A Farad
|-
| micro-Farad
| μF
| 10<sup>-6</sup>
| 0.000001
| A millionth
|-
| nano-Farad
| nF
| 10<sup>-9</sup>
| 0.000000001
| A thousand millionth
|-
| pico-Farad
| pF
| 10<sup>-12</sup>
| 0.000000000001
| A trillionth
|}


[[Category:Secondary]]
[[Category:Terminology]]
[[Category:Electronics and Control]]