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Homework Help: Current Division question

  1. Oct 7, 2013 #1
    Can someone tell me why the current I is negative and not positive?

    Im guessing the equation should be:
    I = (-2)(6||3)/(6). But why the negative sign?
     

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  3. Oct 8, 2013 #2

    ehild

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    Well, the current has to flow in the opposite direction as indicated.

    ehild
     
  4. Oct 8, 2013 #3
    Are there any general rules to follow because I'm sure most circuits wont be as obvious
     
  5. Oct 8, 2013 #4

    ehild

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    There are Kirchhoff's Laws.

    The 2mA current of the current source flows out of the top junction, so the same current has to flow in through the resistors. The sum of the currents flowing in is equal to the sum of the outflowing currents according to Kirchhoff's Current Law. So the current flows upward through the 2 kΩ resistor.

    ehild
     

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