- Dimensions of Physical Quantities and Constants
Dimensions of a Physical Quantity
Dimensions of a physical quantity are the powers to which the fundamental units of length, mass and time must be raised to represent the given physical quantity. They are represented by square brackets around the quantity.
Dimensions of the 7 base quantities are – Length [L], Mass [M], time [T], electric current [A], thermodynamic temperature [K], luminous intensity [cd] and amount of substance [mol].
Examples, Volume = Length x Breadth x Height = [L] x [L] x [L] = [L]3= [L3]
Force = Mass x Acceleration = [M][L]/[T]2= [M L T-2]
The other dimensions for a quantity are always 0. For example, for volume only length has 3 dimensions but the mass, time etc have 0 dimensions. Zero dimension is represented by superscript 0 like [M0].
Dimensions do not take into account the magnitude of a quantity.