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Homework Help: Finding current from a circuit

  1. Feb 9, 2010 #1
    1. The problem statement, all variables and given/known data

    http://img638.imageshack.us/img638/2416/64523221.jpg [Broken]

    2. Relevant equations

    3. The attempt at a solution

    My approach at this problem is using the voltage division law:

    I first need to find the voltage at the 12 ohm, this can be done by the following using voltage division law.

    Vb = (0.04 * 13)/ 41
    Va = (0.04 * 28)/ 41

    then we subtract the two, is this true?
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Feb 9, 2010 #2


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    Homework Helper

    Let i branch out. i1 flows in upper loop and i2 flows in the lover loop.
    Apply Kirchhoff law.
    For upper loop
    -12i -17i1 = 0...(1)
    For lower loop
    -12i - 24 i2 = 0...(2)
    Similarly write down the equation for the left side loop which contains the voltage source and solve the equations to find i.
  4. Feb 10, 2010 #3
    is the left side equal to:

    40mV - 28i = 0
  5. Feb 10, 2010 #4


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    Homework Helper

    No. i1 and i2 are in the opposite direction.
    So it should be
    40 mV = 16*i1 - 12*i2
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