Editing Physical quantity (section)

=== Base quantities ===
{{main|Base quantities}}

A systems of quantities relates physical quantities, and due to this dependence, a limited number of quantities can serve as a basis in terms of which the dimensions of all the remaining quantities of the system can be defined. A set of mutually independent quantities may be chosen by convention to act as such a set, and are called base quantities. The seven base quantities of the [[International System of Quantities]] (ISQ) and their corresponding [[SI]] units and dimensions are listed in the following table.<ref name="SIBrochure9thEd">{{citation |title=The International System of Units (SI) |author=International Bureau of Weights and Measures |author-link=New SI |date=20 May 2019  |edition=9th |isbn=978-92-822-2272-0 |url=https://www.bipm.org/utils/common/pdf/si-brochure/SI-Brochure-9.pdf| archive-url = https://web.archive.org/web/20211018184555/https://www.bipm.org/documents/20126/41483022/SI-Brochure-9.pdf/fcf090b2-04e6-88cc-1149-c3e029ad8232 |archive-date=18 October 2021 |url-status=live}}</ref>{{rp|page=136}} Other conventions may have a different number of [[Base unit (measurement)|base unit]]s (e.g. the [[CGS]] and [[Mks system of units|MKS]] systems of units).

{| class="wikitable"
|+ style="font-size:larger;font-weight:bold;"|[[International System of Quantities]] base quantities
! colspan=2|Quantity
! colspan=2|SI unit
! rowspan=2|Dimension<br>symbol
|-
! Name(s)
! (Common) symbol(s)
! Name
! Symbol
|-
| [[Length]]
| ''l'', ''x'', ''r''
| [[metre]]
| m 
| L
|-
| [[Time]] 
| ''t'' 
| [[second]]
| s 
| T
|-
| [[Mass]] 
| ''m'' 
| [[kilogram]]
| kg 
| M
|-
| [[Thermodynamic temperature]] 
| ''T''
| [[kelvin]]
| K 
| Θ
|-
| [[Amount of substance]] 
| ''n''
| [[Mole (unit)|mole]] 
| mol 
| N
|-
| [[Electric current]] || ''i, I''
| [[ampere]]
| A
| I
|-
| [[Luminous intensity]] || ''I''<sub>v</sub>
| [[candela]] 
| cd 
| J
|}

The angular quantities, [[plane angle]] and [[solid angle]], are defined as derived dimensionless quantities in the SI. For some relations, their units [[radian]] and [[steradian]] can be written explicitly to emphasize the fact that the quantity involves plane or solid angles.<ref name="SIBrochure9thEd"/>{{rp|page=137}}