Series and parallel circuits

Learning objectives

To insist on the fact that, in order for it to function, an electrical circuit must be closed.
To make the linkage between a real electrical setup and a conventional diagram of that setup.
To show that the current passing through the lamps is different in different types of circuits.

A dipole is an electrical conductor with two poles (also called terminals). An electric circuit is an association of dipoles connected to one another by conducting wires.

In order for a current to flow in the circuit, one of the dipoles must be a source of current (generator) and the circuit must be closed.

Two dipoles are in series when they share only a single terminal and, between shared terminals, there is no branching toward another dipole.
Two dipoles are in parallel (or in a branched circuit) if their two pairs of terminals are shared.