Electronics history has been marked by the introduction of components that have opened the doors to new solutions and technology. The real revolution took place with the transistor, preceded by the diode, which marked the definitive birth of digital electronics, leading to the introduction of microprocessors.

Ohm's law unites in one single formula the quantities involved in a circuit: tension (V), current (I) and resistance (R). It involves three equivalent expressions that are derived from simple algebraic operations on the basic formula.