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. Other conventions may have a different number of fundamental units (e.g. the CGS and MKS systems of units).
| 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 | |
| Time | t | second | s | |
| Mass | m | kilogram | kg | |
| Temperature | T, θ | kelvin | K | |
| Amount of substance, number of moles | n | mole | mol | |
| Electric current | i, I | ampere | A | |
| Luminous intensity | Iv | candela | Cd | |
| Plane angle | α, β, γ, θ, φ, χ | radian | rad | dimensionless |
| Solid angle | ω, Ω | steradian | sr | dimensionless |
The last two angular units; plane angle and solid angle are subsidiary units used in the SI, but treated dimensionless. The subsidiary units are used for convenience to differentiate between a truly dimensionless quantity (pure number) and an angle, which are different measurements.
Read more about this topic: Physical Quantity
Famous quotes containing the words base and/or quantities:
“Jealousy is both reasonable and belongs to reasonable men, while envy is base and belongs to the base, for the one makes himself get good things by jealousy, while the other does not allow his neighbour to have them through envy.”
—Aristotle (384–322 B.C.)
“James Brown and Frank Sinatra are two different quantities in the universe. They represent two different experiences of the world.”
—Imamu Amiri Baraka [Everett Leroi Jones] (b. 1934)