What Is the Effective Resistance Between A and F?

AI Thread Summary
The discussion revolves around calculating the effective resistance between points A and F in a circuit. Participants explore different configurations, debating whether resistors are in parallel or if certain paths can be ignored. Initial calculations suggest an effective resistance of 1Ω or 2/3Ω, while another perspective notes that ignoring loops leads to a resistance of 6Ω. Clarifications are provided regarding the implications of zero-resistance wires and the need to redraw the circuit for accurate analysis. The conversation emphasizes the importance of correctly identifying node connections to determine the overall resistance accurately.
niktoo1
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Calculate the effective resistance between A and F

Initially, I thought that the first resistance is ignored and the current takes the lower path. Then 2Ω and 2Ω are in parallel giving an effective resistance of 1Ω.

However, it could also be that all three are in parallel and thus give an effective resistance of 2/3 Ω.
If the upper and lower loops are ignored, the resistance is 6Ω!
What is the correct answer??
 

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hi niktoo1! welcome to pf! :smile:
niktoo1 said:
Initially, I thought that the first resistance is ignored and the current takes the lower path.

hint: wouldn't that only be if the current through BC and CD was flowing the same way? :wink:
However, it could also be that all three are in parallel and thus give an effective resistance of 2/3 Ω.
If the upper and lower loops are ignored, the resistance is 6Ω!

hint: if two points are shown joined by a zero-resistance wire, then they must be at the same potential

so you can re-draw the diagram omitting the wire completely, and showing those two points as the same point :wink:
 
Don't ignore anything. Redraw realizing that A, B, and D are the same node and C, E, and F are also the same.
 
attachment.php?attachmentid=65681&stc=1&d=1389875734.jpg
 

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tiny-tim said:
so you can re-draw the diagram omitting the wire completely, and showing those two points as the same point :wink:


Does that mean that each resistor is in parallel with each other?
 
niktoo1 said:
Does that mean that each resistor is in parallel with each other?

what diagram do you get? (mark it with A BD and CE as in the original diagram)
 
niktoo1 said:
Does that mean that each resistor is in parallel with each other?

Which part of post #4 did you not understand?
 

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