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Equivalent resistance with a short circuit

  1. Sep 7, 2014 #1
    1. The problem statement, all variables and given/known data
    Find the equivalent resistance of the circuit shown below.


    2. Relevant equations
    R=[itex]\Sigma_{i}[/itex]R[itex]_{i}[/itex]
    1/R=[itex]\Sigma_{i}[/itex]1/R[itex]_{i}[/itex]

    3. The attempt at a solution
    I'm having a lot of trouble understanding how this circuit can be simplified. All I see is a big short circuit where the only element that matters is R[itex]_{4}[/itex]. What I tried was considering R[itex]_{2}[/itex] and R[itex]_{3}[/itex] as being in parallel, but I still see a short circuit happening. I don't think I understand how short-circuits behave, because I don't think the equivalent resistance is simply R[itex]_{4}[/itex]. Any guidance would be greatly appreciated (also sorry for the terrible drawing)
     

    Attached Files:

  2. jcsd
  3. Sep 7, 2014 #2

    gneill

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    Staff: Mentor

    Hi sun18, Welcome to Physics Forums.

    Your intuition is correct; The subnetwork consisting of R1 through R3 is bypassed by the wire running from the top terminal to R4. A short circuit is equivalent to a resistance of zero Ohms, so anything in parallel with it is effectively bypassed (A zero Ohm resistance in parallel with any other resistor value is zero).
     
  4. Sep 7, 2014 #3
    Thanks so much for the response gneill. I guess I was overthinking it instead of concluding the obvious.
     
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