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Homework Help: Simple net resistance problem

  1. Feb 19, 2016 #1
    1. The problem statement, all variables and given/known data


    So I am given the above image, and I am told to calculate the voltage in the circuit.

    2. Relevant equations

    V = IR
    R_net = (1/R_1 + 1/R_2 + ... + 1/R_n)^-1 for parallel resistors

    3. The attempt at a solution

    So with a lot of these sort of problems, my biggest challenge is redrawing the circuit into something that I can more intuitively understand. However, I'm having a fair bit of trouble understanding what exactly is going on here - would the open wires with no resistors produce short circuits?

    Once I can find the net resistance, the problem is straightforward: V = IR and plug and chug.

    Turns out that if I treat all three resistors as in parallel I get the right answer, but I cant figure out how the above diagram could be converted into a simple 3 resistors in parallel.

    Any help is appreciated.
  2. jcsd
  3. Feb 19, 2016 #2


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    Staff: Mentor

  4. Feb 19, 2016 #3
  5. Feb 19, 2016 #4


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    Staff: Mentor

    It is preferable to UPLOAD an image and make it visible in the thread so that helpers do not have to follow a link in order to see it.
  6. Feb 19, 2016 #5


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    Homework Helper
    Gold Member

    Remove the middle 30Ω. What do you get?
  7. Feb 19, 2016 #6


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    Staff: Mentor

    Starting at terminal 'a', use different coloured pencils to trace each independent path that current can follow to get to 'b'.
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