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Finding equivalent resistance in complicated circuit

  1. Feb 15, 2010 #1
    1. The problem statement, all variables and given/known data

    Problem: What single, equivalent resistor could replace all of the resistors in this circuit?
    Given R1 = 4, R2 = 5, R3 = 14, R4 = 9

    2. Relevant equations

    In series, R1 + R2... = Req
    Parallel, 1/R1 + 1/R2... = 1/Req

    3. The attempt at a solution

    I have tried multiple different possibilities of series/parallel. I thought for sure that R2/R4 are in parallel, that R1 was in series with 2/4 and that R3 was in parallel with 1/2/4. When I tried this answer, I got feedback that I was wrong.
     

    Attached Files:

  2. jcsd
  3. Feb 15, 2010 #2
    I would say that R2 and R4 are in parallel, call it R5
    R5 is in series with R3, call it R6
    R6 is in parallel with R1
     
  4. Feb 15, 2010 #3
    Your first conclusion was correct, But R1 is not in series with R2/R4.

    Two resistances are in series:
    - if they are connected to each other with a wire.
    - if nothing else connects to this wire.

    The second condition fails because the battery is also connected to the connection between
    R1 and R2/R4

    try to look only at what is connected to what, and not where the resistances are drawn. direction.
     
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