# System of Units

A complete set of units, both fundamental and derived for all kinds of physical quantities is called system of units.

SI system it is known as international system of units and is an extended system of units applied to whole physics. There are seven fundamental quantities in this system. These quantities and their units are given in Table.

Table Unit and Symbol of Quantities

 Quantity Unit Symbol Length Meter m Mass Kilogram kg Time Second s Electric current Ampere A Temperature Kelvin K Amount of substance Mole mol Luminous intensity Candela cd

Besides the seven fundamental units given in Table 1, two supplementary units are also defined: radian (rad) for plane angle and steradian (sr) for solid angle.