Switches, fuses and circuit breakers are examples of some of the electrical parts which can connect or disconnect a circuit to a source of current. A diode does it for alternating current, but only...
Three basic parts of a circuit are: 1. Active components = source of energy 2. Transmission Lines = wiring and control devices 3. Passive components = load or user of energy
In order to have the electricity or the flow or electrons going around the circuit, the circuit must be closed. If it is not closed then electrons cannot flow.
Generally a circuit breaker (like a light switch) But I guess you could use a resistor of the right resistance If you are talking about the circuit breaker there is an electromagnetic coil in it...