Some electrical outlets that power common electrical devices use simple circuits. Many of these outlets have a switch that can power on and off the device, much like the switch that turns a light on and off. An electrical air conditioning unit can also use a simple circuit. Electric circuit, path for transmitting electric current. An electric circuit includes a device that gives energy to the charged particles constituting the current, such as a battery or a generator; devices that use current, such as lamps, electric motors, or computers; and the connecting wires or transmission lines.