Open-circuit voltage

Voltage in the context of electric circuits is a quantity that can be associated with any (ordered) pair of points. It is defined as the amount of work done on a charge by the electric field in the circuit while it is moved from the first point to the second. Even for two points in a circuit that are not directly connected by a circuit element (i.e., an open circuit), a voltage can be defined. An switch that has been opened is a particular instance of an open circuit.

Decoding work done

Identification of bottleneck

at open circuits are difficult for many students in electrical engineering or physics courses. Often, this difficulty occurs first when voltages across open switches are considered.