What is the function of an SPDT switch?

An SPDT (Single Pole Double Throw) switch is designed to control a single circuit by connecting it to one of two different outputs. The unique feature of an SPDT switch is that it has one input terminal and two output terminals, allowing it to switch the flow of electricity between two distinct paths. When the switch is toggled, the current can flow to either of the two terminals, effectively allowing the user to select which circuit to connect to at any given moment.

This functionality is particularly useful in various applications, such as selecting between two different power outputs, controlling multiple devices from a single point, or switching signals in communication equipment. An SPDT switch essentially serves as a mechanism for choosing one of two options in a circuit, providing versatility in electrical configurations.

In contrast, the other options describe switch functions that either do not accurately represent what an SPDT switch can do or involve configurations that exceed the capabilities of a standard SPDT switch. For example, stating that a single circuit is opened or closed implies a basic on-off switch functionality, which does not utilize the dual output capability of the SPDT switch.