What is the primary function of a switch in an electrical circuit?

The primary function of a switch in an electrical circuit is to interrupt the current delivered to the load. When a switch is closed, it allows current to flow through the circuit, enabling the connected device to operate. Conversely, when the switch is opened, it breaks the circuit and stops the flow of current, thereby turning off the device connected to the circuit. This capability to control the flow of electricity makes switches essential components in a wide range of electrical applications, allowing users to easily and safely manage power to various devices.

The other options highlight functions that are not relevant to the primary role of a switch. For instance, providing electrical energy to the circuit is not a function of a switch, but rather the role of a power source. Measuring voltage levels relates to instruments like voltmeters, and converting electrical energy into mechanical energy pertains to devices such as motors. These functions are important in their own contexts, but they do not define what a switch does within an electrical system.