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. A switch that has been opened is a particular instance of an open circuit.

The voltage in open circuits has been the focus of a decoding interview as well as of extensive research on student understanding (within Physics Education Research and Engineering Education Research).

Decoding work done

Identification of bottleneck

The voltage in an open circuit is a difficult concept for many students in electrical engineering or physics courses. Often, this difficulty occurs first when voltages across open switches are considered. As there is no direct conducting path between the two terminals ("ends") of the open circuit, and hence no current flows between the two points across the open circuit, it is difficult for students to grasp that (1) the concept of a voltage still applies and (2) this voltage in most practical cases has a value other than zero.