1. Derivation of electrical units

The realization (or determination) of a unit results from the application of its definition given within the framework of the SI, the international system of units [R 50][3] . The first three of the seven SI base units are length (m), mass (kg) and time (s). These units are used to define derived units such as force (newton, noted N), energy (joule, noted J) and power (watt, noted W). They are also involved in the definition of the ampere (A), the fourth SI base unit that links electrical units to mechanical units (figure