Base quantities::Physical quantity


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Base quantities {{#invoke:main|main}} Base quantities are those quantities on the basis of which other quantities can be expressed. The seven base quantities of the International System of Quantities (ISQ) and their corresponding SI units and dimensions are listed in the following table. Other conventions may have a different number of base units (e.g. the CGS and MKS systems of units).

International System of Units base quantities
Quantity name/s (Common) Quantity symbol/s SI unit name SI unit symbol Dimension symbol
Length, width, height, depth a, b, c, d, h, l, r, s, w, x, y, z metre m L
Time t, τ second s T
Mass m kilogram kg M
Temperature T, θ kelvin K Θ
Amount of substance n mole mol N
Electric current i, I ampere A I
Luminous intensity Iv candela cd J
Plane angle α, β, γ, θ, φ, χ radian rad 1
Solid angle ω, Ω steradian sr 1

The last two angular units, plane angle and solid angle, are subsidiary units used in the SI, but are treated as dimensionless. The subsidiary units are used for convenience to differentiate between a truly dimensionless quantity (pure number) and an angle, which are different measurements.

Physical quantity sections
Intro  Symbols, nomenclature  Units and dimensions  Base quantities  General derived quantities  See also  References  Sources  

Base quantities
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