# How come no current flows through the wire of no resistance in this short circuit? [closed]

I am currently solving for the equivalent Norton current through this circuit. To solve for it, I turned my schematic into an open circuit (not pictured) and I need to calculate the current through the wire of zero resistance (top). However, my answer key says no current runs through the top wire. How come? Any help would be appreciated. • Hi and welcome to the Physics SE! Please note that we don't answer homework or worked example type questions. Please see this Meta post on asking homework/exercise questions and this Meta post for "check my work" problems. Jul 4, 2017 at 14:58
• Label your voltage source "V" and the ends of the wire "B" and "C". Now mentally cut the wire. Then find the voltages for B and C as a function of V. When you know the voltage at B and the voltage at C, the answer will become obvious. Jul 4, 2017 at 15:17

For the moment forget about the short circuit.

What you have is two potential dividers fed from the same voltage source which I have assumed is 3 V. Since both sets of resistors are in the ratio of 2:1 the voltages across them must also be in that ratio as shown in the diagram.

Node C has a potential of 2 V lower than that of node B and node D has a potential of 2 V lower than that of node B.

So the potential difference between nodes C and D is zero.

Connecting a conductor between nodes C and D will result in no current flowing through the conductor.