The way a fuse works and the purpose of a fuse in a household circuit is that the current passing through the fuse flows through a small metallic strip, which melts if the current is large enough. What happens when a fuse is not used in a circuit? When a fuse is not used, excessive currents could damage circuit elements, overheat wires, and perhaps cause a fire. In most modern homes, circuit breakers are used in place of fuses. The way a circuit breaker works is when the current in a circuit exceeds some value, typically 15A, the circuit breaker acts as a switch and opens the circuit.

To demonstrate our knowledge of the components of circuits, we decided to build several circuits of our own, each displaying different ideas. For fuses, we decided to build a circuit that only contained the power source and a fuse. By doing this we anticipated that if we sent a high enough current through the fuse that it would burn out the fuse and the circuit will no longer work. In this demonstration, we did not hook up any other devices to the circuit so that the current could flow through the fuse. We knew that the amount of power that we were sending through the circuit would produce a high enough current to exceed the fuse capacity. Sure enough when we completed the circuit, it did not take long for the current to overload the fuse and have it burn the thin metal piece inside of the fuse. We then added resistors to this circuit. We predicted that because more resistance was added to the circuit, less current would flow through the fuse. Therefore, the fuse would not burn out as it did before. Indeed, with two resistors present, the fuse did not burn out. So our predictions were correct and we got a chance to see what the purpose of a fuse would be in a circuit.

Another circuit we built was to demonstrate the use of a switch. To do this we connected two lights in parallel and before the first light, we put switch. The purpose of the switch was to control the flow of the current to the light. The way this circuit was built made it possible for one light to be on all the time while flipping the switch was required to turn the second light on. The switch enabled us to turn the first light on and off independently from the second light. The way the switched work was that when it was off it made an open circuit where t<0 so current could not go across and light up the first light. However when the switch was on it created a closed circuit where t>0 so now the current was able to flow through the circuit make the bulb light up. Another circuit that we created was one that we could use the switch to control both the lights. To do this we put the switch right after the power source and still had the lights in parallel.