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Electric circuit problem, finding current through a resistor

  1. May 19, 2013 #1
    1. The diagram attached shows part of an electric circuit. What is the current through resistor R1?

    To summarize:
    I=6.0 A
    R1 = 11.0 Ω
    R2 = 33.0 Ω
    R3 = 67.0 Ω

    R2 and R3 are in parallel, and R1 and R2 and 3 are in parallel.

    I know we aren't supposed to attach pictures of questions, but a diagram does make my question a lot easier to understand.

    2. Relevant equations

    IT in series = I1=I2=I3
    IT in parallel = I1+I2+I3
    RT in series = R1+R2+R3
    RT in parallel = [(1/R1)+(1/R2)+(1/R3)]-1

    3. The attempt at a solution

    Using the resistor laws, I can find resistance of R2 and 3 by (1/33+1/67)-1.

    Using Kirchoff's Laws, I know that the resistance coming out has to equal the 6.0 A.

    But I don't get how all this information is relevant. The question doesn't give me voltage or any other information and I don't know how to figure out how much current goes through each resistor.

    Attached Files:

  2. jcsd
  3. May 19, 2013 #2
    Notice that ALL of the resistors are in parallel. Find the voltage across all of them, then find the current through each one.
  4. May 19, 2013 #3


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    Staff: Mentor

    What's the net resistance of the circuit?
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