Charge and Current

Electrical engineering is entirely based on the movement of charge carriers. Forces in electrical machines are forces on moving electrons. Accelerated charge carriers let antennas send and receive. And the diffusion of electrons into impurities in semiconductor crystals forms the basis of all transistor functions. In this chapter, the essential properties of the charge, i.e. its composition of elementary charges and its conservation, will be presented. The relationship between charge, current density, and current will also be laid out. It should also become clear which assumptions lead to Ohm’s law and under which circumstances deviations occur.