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Homework Help: Circuits and electromotive force

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

    [PLAIN]http://img535.imageshack.us/img535/8527/76966242.jpg [Broken]

    sorry for the image, i made it very quickly

    given this circuit find

    1) the current (I) in the circuit
    2) Vab of the battery that has potential 16V
    3) Vac

    1) how can i find the current with two batteries? if we had only the first one it would be

    Vab = E - Ir1

    but Vab = I(R1 + R2)
    so we have

    I(R1+R2) = E - Ir1 => I = E/(R1+R2+r1)

    so i guess that would be the I with 1 battery, but with 2? :(

    2) is this correct?

    Vab = E - Ir1
    we have I from (1) so we have the Vab

    3) im not sure about this

    Vac = E - IR1 - Ir2

    please someone, guide me

    thanks in advance
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
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