Finding Equivalent Resistance in Resistor Network - Can You Help?

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Discussion Overview

The discussion revolves around finding the equivalent resistance in a resistor network between points A and B. Participants are analyzing a circuit diagram and attempting to clarify their reasoning regarding the arrangement of resistors, including parallel and series configurations.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that R5 and R6 are in parallel, forming Rp56, which is then in parallel with R3, and the entire arrangement is in series with R4, leading to a total resistance of 5k.
  • Another participant challenges this interpretation, stating that the circuit is more complex and recommends applying Kirchhoff's Law to analyze the subchains of the circuit.
  • A different participant emphasizes that for resistors to be in parallel, they must have the same potentials at both ends, indicating that R5 and R6 do not meet this criterion.
  • One participant claims to have arrived at the correct answer by determining that R4 and R3 are in parallel, yielding 2k, which is then in series with R5, and this equivalent resistance is in parallel with R6.
  • Another participant confirms the previous claim, stating that they arrived at the same conclusion regarding the equivalent resistance.

Areas of Agreement / Disagreement

Participants express differing views on the arrangement of the resistors and the application of circuit analysis techniques. There is no consensus on the correct method or final answer, as some participants propose different configurations and calculations.

Contextual Notes

Participants reference the need to redraw the circuit and consider the connections between resistors, indicating that assumptions about the circuit layout may affect the analysis. The discussion highlights the complexity of the circuit and the importance of accurately identifying parallel and series relationships.

kdinser
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Can someone tell me where I'm going wrong here?
I'm uploading a jpeg of the circuit, I'm supposed to find the equivalent resistance between A and B.

To me, it looks like R5 and R6 are in parallel and forming Rp56. From there I'm assuming that Rp56 would be in parallel with R3 and then that whole top part (R5, R6, and R3) would be in series with R4.

Can someone point out where I'm making my error? I'm coming up with a total resistance of 5k and the answer should be 4k.
 

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kdinser said:
To me, it looks like R5 and R6 are in parallel and forming Rp56. From there I'm assuming that Rp56 would be in parallel with R3
This is incorrect because the chain is more complex due to the different interconnecting wires. What you need to do is to apply Kirchoff's Law. Do you know this procedure ? You basically apply charge conservation and energy conservation on each subchain. So, the first thing to do is to detect each subchain (you have three such chaines in your case).

marlon
 
kdinser said:
To me, it looks like R5 and R6 are in parallel and forming Rp56. From there I'm assuming that Rp56 would be in parallel with R3 and then that whole top part (R5, R6, and R3) would be in series with R4.

To be in parallel, the two resistors have to have the same potentials at BOTH ends, which means both their ends touch each other. Here 5 and 6 only touch at one end. Shorten all the wires and redraw the circuit without wires and see which resistors touch at both ends. I did it and came up with 4k as the answer.
 
I think I have it, at least I'm coming up with the correct answer now.

Going back to the original diagram, R4 and R3 are in parallel giving a resistance of 2k which is in series with R5. This equivalent resistance is then in parallel with R6.

Sound right? Thanks for the help guys.

Oh, and thanks for not just spewing out the answer, it makes a lot more sense now.

Keith
 
kdinser said:
Going back to the original diagram, R4 and R3 are in parallel giving a resistance of 2k which is in series with R5. This equivalent resistance is then in parallel with R6.

Sound right?

That's the way I got it.
 

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