Answer: when a circuit is completed (it allows the flow of electrons which causes the light bulb to produce light).
Explanation:
A circuit is described as an electrical setup that is consists of a light bulb, a switch, a wire, a battery which is arranged to allow the flow of electric current. The major components of the electrical circuit includes:
--> The BATTERY which is the source of voltage to the circuit,
--> the WIRE which is the conductive path,
--> the LIGHT BULB which is the load that needs electrical power to operate and
--> the SWITCH which is the controller.
When a circuit is COMPLETED when electrons can flow from one end of a battery all the way around, through the wires, to the other end of the battery. Along its way, it will carry electrons to electrical objects that are connected to it like the light bulb and make it to produce light.
There are different types of electric circuit which are designed to create a conductive path of current or electricity. They include:
--> closed circuit
--> open circuit
--> short circuit
--> parallel circuit
--> series circuit.