Electrical circuits enable electricity to flow from the power source, such as a battery, to an electrical device and back to the power source. However, there are different methods for wiring a circuit, depending on the purpose. Demonstrating the different circuits are good fifth-grade science fair projects.
Battery Parallel Circuits
Parallel circuits are used for most of the wiring in your home. If you wire two batteries together for a fifth-grade science fair project, you combine the endurance of the batteries, but the voltage remains the same as one battery. Line up two batteries and connect a wire from the positive terminal of one battery to the positive terminal of the second battery. Do the same for the negative terminals. Connect to a light bulb another battery that is the same voltage as the two you’ve wired. Connect the parallel batteries to another light bulb. Make a note of the time and see which light bulb stops working first. The parallel batteries will power the light bulb for double the time of the single battery.
Battery Series Circuits
A series circuit is the simplest of all methods. It combines the voltage from each battery in the circuit to increase the total voltage. For example, if you wire three 1.5 volt batteries in a series, the combined voltage is 4.5 volts. Line up three batteries. Attach a wire to the negative terminal of the first battery and the opposite end to the positive terminal of the second battery. Attach the end of another wire to the negative terminal of the second battery and the opposite end to the positive terminal of a third battery. The batteries are wired in series and produce three times the voltage of one battery. You can demonstrate this by attaching a wire to the positive terminal of the first battery and attaching a wire to the negative terminal of the third battery. Connect the wires to a light bulb, and the circuit is complete.
Combine Parallel and Series Circuits
This method utilizes the benefits of both types of circuits; it increases voltage and endurance. So if you wire four batteries using this method, you get double the output voltage, and they last twice as long. Place four batteries on a table and label them 1 through 4. Attach a wire to the negative terminal of battery 1 and the positive terminal of battery 2. Do the same for battery 3 and 4. Now attach a wire to the positive terminal of battery 1 and the positive terminal of battery 3. Attach a wire from the negative terminal of battery 2 to the negative terminal of battery 4. Wire a light bulb to the positive terminal of battery 1 and the negative terminal of battery 2 to complete the combined circuit.
Series vs Parallel
You can demonstrate the difference between the two circuits by placing the batteries you’ve wired next to each other. Ensure both are connected to a light bulb. Disconnect one of the wires connecting the series batteries. The light goes out because the circuit is broken. Disconnect one of the wires between the two parallel batteries; the light stays on. This is because each battery has its own circuit.