Physical quantity, units and dimensions
A quantity that can be measured by instrument, clearly defined and has proper units is called physical quantity. Physical quantities are classified as fundamental and derived quantities.
The physical quantity which does not depend on any other physical quantity is called a fundamental physical quantity such as length; mass and time are called fundamental units.
The units that can be obtained from fundamental units are called derived units.
System of units:-
Mechanical Physical Quantities (derived)
Electrical Physical Quantities (derived) :-