27.2: Introduction

An electric circuit provides a complete path through which electrons may flow. There are two basic types of circuits: series and parallel. Devices in a series circuit are connected in one continuous loop while devices within a parallel circuit are connected in multiple loops. A short circuit is a path of least resistance in the electrical circuit which bypasses the devices that the circuit is intended to operate. When there is a short circuit, wiring may become hot. Circuit diagrams show how the different types of circuits are connected together. The lines in a circuit diagram represent wires.

The resistance is added differently in each type of circuit because of how current flows across each device in series versus parallel circuits.

Table \(\PageIndex{1}\): Series and Parallel Resistance

Series Circuit Resistance	Parallel Circuit Resistance
\(R = R_1 + R_2 + R_3\)	\(\dfrac {1}{R} = \dfrac {1}{R_1} + \dfrac {1}{R_2} +\dfrac {1}{R_3}\)

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