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Homework Help: Current flowing in a Resistor

  1. May 20, 2013 #1
    1. The problem statement, all variables and given/known data
    AB, BC and CD are three resistors connected together at B and C. AB = 12 ohms, BC = 7 ohms, CD = 6 ohms. A battery of emf 48V and internal resistance 0.5 ohms has it positive pole connected to B and its negative connected to D. A battery of emf 74V and internal resistance 1 ohm has its positive pole connected to A and its negative pole connected to C. Find the current flowing in BC.

    2. Relevant equations
    E = I(R +r)
    V = IR

    3. The attempt at a solution

    To be honest, I'm clueless.

    I tried using E = I(R + r) but unsure how to add up resistors in a triangle :S
  2. jcsd
  3. May 20, 2013 #2
    I'm not sure of your circuit. Whnat does "connected together at B and C mean?
  4. May 20, 2013 #3
    I am not exactly sure either, I've just copied word for word the question my professor has given.
  5. May 20, 2013 #4
    You should be able to draw the schematic with two current loops. Using Kirchoff's law, you can have two equations with two currents. Solve them simultaneously.
  6. May 20, 2013 #5


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    Gold Member

    Then tell your professor that he has not provided enough information for there to be a solution.
  7. May 20, 2013 #6


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    Staff: Mentor

    An interpretation that seems to fit the bill:


    Attached Files:

  8. May 20, 2013 #7
    I think that there are 3 resistors in series. There are 4 terminals. 12 ohms between a and B, 7 ohms between B and C and 6 ohms between C and D. 48 volt battery with .5 ohm internal resistance connected with + to B and - to D.
  9. May 20, 2013 #8
    Using gneil's diagram I'd just split it into 2 loops and then as 'barryj' suggested, solve them simultaneously.

    Will try this and check if its right.

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