Ohm's Law, Branch Relationships, and Sources

Summary

Ohm's law describes the relationship between voltage, current, and resistance for resistive circuits. This chapter describes Ohm's law and the related circuit elements, resistors, current sources, and voltage sources. It also covers the more general idea of branch relationships, the relation between the voltage across a circuit element and the current through a circuit element, for resistors, voltage sources, and current sources. In electronics, a circuit element is a description (model) and a schematic symbol of a physical device in an electric or electronic circuit. Ohm's law is also valid for currents and voltages that vary as a function of time. Ohm's law applies beyond resistive circuits, where the ratio of the voltage function to the current function is more generally called impedance. Resistance is one type of impedance, a subset of impedance.