SI Base Units List

There are 7 SI base units. The seven units along with their SI unit and symbol are given below:

1. Unit of length, meter (m): Meter is the SI unit of length and is defined by taking the fixed value of the speed of light in vacuum. It is expressed as m.s^-1.
2. Unit of mass, kilogram (kg): Kilogram is the SI unit of mass and is defined by taking the fixed value of the Planck constant. It is expressed as kg.m².s^-1.
3. Unit of time, second (s): Second is the SI unit of time and is defined by taking the fixed value of Cesium frequency. It is expressed as s¹.
4. Unit of electric current, ampere (A): Ampere is the SI unit of electric current and is defined by taking the fixed value of the elementary charge.
5. Unit of thermodynamic temperature, Kelvin (K): Kelvin is the SI unit of thermodynamic temperature and is defined by taking the fixed value of Boltzmann constant k = 1.380649×10^-23.
6. Unit of the amount of substance, mole (mol): Mole is the SI unit of the amount of substance and is defined by the fixed value of Avogadro constant N_A. One mole contains 6.02214076×10²³ elementary entities and is expressed as mol^-1.
7. Unit of luminous intensity, candela (cd): Candela is the SI unit of luminous intensity and is defined by the fixed value of the luminous efficacy.

It should be noted that these 7 units are assumed to be mutually independent and hence are called base units.