Closed circuit

A closed circuit is an unbroken conducting loop: an open switch or a disconnected wire breaks the path, so there is no continuous flow around the circuit.

For charge to keep flowing, it needs a closed circuit: a complete conducting path from one terminal of a cell, through the components, to the other terminal.

A steady current needs both a source of potential difference and a closed circuit. A cell or battery provides a potential difference, transferring energy to the charges and driving their movement. The circuit must also provide a complete conducting path from one terminal of the source, through the components, and back to the other terminal.