Electrical Circuits
We have learned that electricity is a form of energy created when electrons flow or move between atoms. A continuous flow of electrons from atom to atom to atom creates an electrical current. An electrical current can be compared to the flow of water through pipes. This current of electricity travels in a path called a circuit.
The Bridge
There are two main kinds of circuits: closed and open. A closed circuit is like a road that crosses over a river by way of a bridge. A bridge allows your car to travel on a road, cross the water, and continue on the other side. In the same way, a closed circuit allows electrical energy (electrons) to continue flowing and moving. A closed circuit has no breaks in it to stop the flow of electricity.
An open circuit is like a road that ends at the rivers edge. When there is no bridge, your car can go no farther. In an open circuit, a similar thing happens. The movement or flow of electrical energy (electrons) is stopped. An open circuit has a break in it that stops the flow of electricity.
Circle of Light
In addition to being open and closed, an electrical circuit can also have a different number of paths. A series circuit has two or more bulbs being powered. One switch turns on both lights. The bulbs have to share the power, so they don’t glow as brightly as a circuit with just one bulb. If one bulb breaks, then the circuit is broken, and neither bulb will light. Series circuits can also have two power sources for one bulb. The bulb will glow more brightly than a circuit with one battery, but it will shine for the same amount of time. An example of this type of series circuit is found in a flashlight.
On the other hand, a parallel circuit has two separate paths bringing electricity to the bulbs. If one bulb breaks, the other one will still light up because it has its own path for electrons to flow. Another type of parallel circuit has the dry cells side-by-side. This will power a device for twice as long. The device will shine just as brightly as the simple circuit. An example of this type of parallel circuit can be found in a TV remote.