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Homework Help: Determine currents of a circuit

  1. Sep 25, 2010 #1
    1. The problem statement, all variables and given/known data

    For the circuit in the figure, determine i1to i5


    2. Relevant equations

    current division: in = (Requivalence / Rn) * itotal
    Requivalence in parallel = R1*R2 / R1+R2

    3. The attempt at a solution

    || (parallel), and +s (series)

    1ohms || 2ohms = Req1
    Req1 || 4ohms = Req2
    Req2 +s 3ohms

    However, note that current i3,4,5 are present. Parallel elements do not share the same current. I have trouble applying the current division.

    If I assume I am only taking i3, i4, and i5, and let i3 be the total current at that particular region, then the Reqv is (2*1)/2+1 meaning 2/3
    Then which Rn should I take?

    The formula for current division is mentioned above.

    Please let me how to solve this problem that involves multiple currents going around.

    Thank you.
  2. jcsd
  3. Sep 25, 2010 #2
    actually problem solved.;
    i figure that in the end i get a series.
    from that series i can find i1, and because the rest are in parallel, i have the same voltage, which is found through the Req3 and i1.

    But if you have anything else to say please do. Thank you!
  4. Sep 26, 2010 #3


    User Avatar
    Science Advisor

    I think you have it OK.

    Work out the result of the 3 parallel resistors, then work out the voltage division between this resistor and the 3 ohms. To do this, you work out the total resistance and find the total current in this from 40 volts. Then IR to get the voltage across the bottom resistors.

    Then you know the voltage across all the bottom resistors (because they are in parallel) so you can work out the currents in each of them.

    Did you get an answer?
  5. Sep 26, 2010 #4
    @ vk6kro
    Yes I did. Thank you for the comment though!
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