# Two parallel wires with no resistance - why it's wrong?

I've built the scheme below in circuit simulator and it didn't work because of "wire loop" mistake. Why it's wrong? Why it's wrong physically?

The simulator is falstad.com/circuit

• Why something is wrong "physically" has little relationship to why a circuit won't work in a simulator. Dec 9 '18 at 16:56
• Which simulator? It might just be upset that it can't determine how much current flows through each wire. Dec 9 '18 at 16:57
• @Andyaka why it doesn't work in a simulator? Dec 9 '18 at 16:58
• Yeah, Falstad will want to know the current in each wire so it can do its cutesy animations. In this circuit, that can't be determined so Falstad will consider it an error. Dec 9 '18 at 17:01
• Circuit simulators deal with idealized wires, which have zero resistance (and zero inductance, and zero capacitance). To model a real-world circuit that looks like what you drew on paper, estimate the resistance of each wire and put resistors into each leg in the circuit simulator. Dec 9 '18 at 17:17