What arrangement of paths would make a circuit not light? For example, where can you NOT place wires in order to keep the circuit working.
1 Answer
There are two basic answers to your question and a whole lot of minor variations.
Let's just consider a power supply, a single light bulb, and some wires. In a functioning circuit there are two terminals on the power supply (or battery) and two terminals on the light bulb. One wire connects between each battery terminal and a different light bulb terminal.
Open Circuit: This is the easiest case because it was probably the setup with which you started. Nothing is connected in a complete circuit. Start with the working circuit and disconnect one terminal. Light goes out. Disconnect more wires if you like, this will not turn the bulb back on.
Short Circuit: If you start with the working circuit and connect an extra wire between the two terminals on the bulb, most of the current will flow through the wire instead of going to the bulb. The bulb will go out. Connecting a wire across the two terminals of the power supply is the equivalent circuit. It will also allow the current to flow in a path which does not include the bulb.
Many other variations are possible if you imagine lots of extra wires or missing wires. But basically each will result in one of the three circuits above. It will work, it will be unconnected, or the circuit will be shorted. It's a good exercise for the student to think through several random cases and see that each reduces to just these three. Recognize that you can connect 10 wires between the same two terminals and they will act just the same as a single wire.
