What is an Open Circuit?

Any circuit which is not complete is called an Open Circuit. A complete circuit which is not performing any actual work can still be a closed circuit. For example, a circuit connected to a dead battery may not perform any work, but it is still a closed circuit.

An electric circuit that has been broken, so that there is no complete path for current flow.

A condition in an electric circuit in which there is no path for current between two points; examples are broken wire and a switch in the open, or off position.

Open circuit voltage is the potential difference between two points in a circuit when a branch (current path) between the points is open-circuited. Open circuit voltage is measured by a voltmeter which has a very high resistance.