What is unit ? What are fundamental unit and derived unit.

 Comparison with certain basic internationally accepted reference standard is called unit.

- Measurement of physical quantity is expressed by number accompanied by a unit.

- Although number of physical quantities are very large we need only limited no. of units for expressing all physical quantities. Since they are interrelated with one another.

- The unit for fundamental or base quantities are called fundamental or base unit.

- Physical quantities which are expressed as combination of fundamental quantities are called derived quantities and their unit are called derived unit.