# Calculating equivalent resistance using loop analysis with no applied voltage

I have a bridge circuit that I am supposed to find an equivalent resistance between points K and P for using loop analysis. I am aware that a delta Y transformation is the much more direct route, however I am required to use loop analysis.

I am having trouble understanding how to do this with no voltage present. I am familiar with using Kirchhoff's Voltage rule and current rule to do a loop analysis and find the overall current when there is a voltage applied. However, when there is no voltage applied I am not sure how the voltage rule applies. I could of course apply a dummy voltage at points K and P which would allow me to calculate the currents and, by Ohm's law, the equivalent resistance.

I've searched the web for loop analysis of resistor circuits but everything I keep finding has a voltage source included. This suggests to me that the dummy voltage is the way to go.

Basically I'm wondering if there is some type of loop analysis method that I am unaware of that does not require a voltage source, or if the dummy voltage method is what the question is asking me to do.

• Normally a constant V is applied to this Wheatstone bridge across K-P but to find the node equiv resistance one can apply a current source then compute the voltage drop to derive Req. – Tony Stewart Sunnyskyguy EE75 Mar 4 at 22:34
• @SunnyskyguyEE75 Sounds like an answer – Redja Mar 4 at 23:07
• Loop analysis is done by the summation of voltage drops across loops. Without any source to deliver power, how can you even find voltage drops in a ckt? – Mitu Raj Mar 5 at 14:53