opencircuit

An open circuit is a circuit in which the conducting path is interrupted, so no current can flow. In electrical terms, it corresponds to an infinite impedance between two points. When a circuit is open, devices connected to the circuit do not receive current and cannot operate.

Distinction: A switch that is open creates an open circuit; unlike a short circuit, which has very low resistance and causes large currents. Open circuits can occur intentionally (as a switch or test point) or due to faults such as broken wires or loose connections. Even with an open path, a potential difference can exist across the open terminals, and there may be residual parasitic effects such as capacitance or leakage.

Measurement and theory: The open-circuit voltage is the voltage across the terminals when the circuit is not delivering current to a load. It is determined with a voltmeter of high input impedance. The open-circuit condition is used in Thevenin analysis, where Voc is the Thevenin voltage of a network, and Isc (short-circuit current) is used with a short to determine Thevenin resistance Rth = Voc / Isc.

Examples: A battery connected to nothing presents an open circuit; a solar panel has a higher open-circuit voltage than under load.

Safety and practical notes: Even though no current flows in an open circuit, the terminals can still hold dangerous voltages. Open circuits are common in testing, fault analysis, and in devices that use switches or removable connections to control whether a circuit is active. See also short circuit, current, voltmeter, and Thevenin equivalents.