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Homework Help: Calculation of equivalent resistance

  1. Jun 22, 2015 #1
    1. The problem statement, all variables and given/known data : Given the circuit diagram, find the equivalent resistance between points P and Q. ngodxd.png

    2. Relevant equations : ΔVloop = 0, ΔIjunction = 0 and V = IR

    3. The attempt at a solution : Eliminating the wires with no resistors and solving for resistance gives me the answer as (11/10) R, which is not the answer. I'm confused as to which resistors are in parallel and which resistors are in series.
    Last edited by a moderator: Jun 22, 2015
  2. jcsd
  3. Jun 22, 2015 #2


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    Perhaps start by numbering the resistors A, B, C etc and post the drawing again.

    Tell us which you think are in series or parallel. For example "I think A is in series/parallel with...."

    Normally this type of problem is simplified by replacing two resistors in series or parallel with one and redrawing the circuit. You've posted the original so show us the first step/simplification that you made.
  4. Jun 22, 2015 #3
    Post your working out. We have no way of knowing where you went wrong (and therefore how to help you/ correct any mistakes) if we can't see your reasoning, but the attempt at the problem appears to be right (eliminate the short wire and simplify using the rules for resistors in series/ parallel).
  5. Jun 22, 2015 #4
    Remember also the rule that if multiple resistors have the same voltage drop associated with them then they are parallel
  6. Jun 23, 2015 #5
    This is how I worked out the circuit. Is it correct? 24ex442.png
  7. Jun 23, 2015 #6


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    Not correct.

    Follow this advice:
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