Find equivalent resistance in this circuit

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Homework Help Overview

The discussion revolves around finding the equivalent resistance between two nodes in a circuit, specifically between nodes A and B. The original poster references a circuit diagram and mentions using Kirchhoff's Current Law (KCL) and Kirchhoff's Voltage Law (KVL) to set up equations for analysis.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss setting up KCL and KVL equations to find the current Iab, while questioning the method of determining the voltage Vab. There is a suggestion to introduce a voltage source to facilitate the analysis.

Discussion Status

Some participants have provided guidance on the approach to take, indicating that the original poster's method of finding Iab is on the right track. However, there remains confusion regarding the details of the calculations and the necessity of solving for Vab independently.

Contextual Notes

There is an emphasis on rearranging equations to express the equivalent resistance Rab in terms of the resistors, without needing to find Vab or Iab as separate values. The discussion reflects a lack of consensus on the clarity of the original poster's approach and the steps involved.

Hyperfluxe
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Homework Statement


http://session.masteringengineering.com/problemAsset/1515645/4/Steif.ch02.p28.jpg
Find the equivalent resistance between node A and B, knowing that Rab = Vab/Iab

Homework Equations


KCL and KVL, I know.


The Attempt at a Solution


There is nothing in series or parallel here, so what I did is set up KCL equations and KVL loop equations (top and bottom loops), so 6 equations with 6 unknowns and I can find Iab. I don't know how to find Vab though...
 
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You don't find Vab, you stick a voltage source there (value of your choosing, or just leave it as a variable, "Vab"). The equivalent resistance Rab is given by the ratio Vab/Iab.

Presumably the Vab variable will cancel out in the workings leaving you with an expression for Rab in terms of R alone.
 
I'm still confused though, is my method of finding Iab correct?
 
Hyperfluxe said:
I'm still confused though, is my method of finding Iab correct?

Well, the approach of finding Iab given a source voltage Vab is correct. But you haven't shown the details of your work so it's not possible to say more.
 
Hyperfluxe said:
I'm still confused though, is my method of finding Iab correct?

You don't need to solve the equations to find Iab or Vab their own.

Rab = Vab/Iab

so reaarange the equations until you get one for the ratio Vab/Iab in terms of the resistors only.
 

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