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Homework Help: Direct current circuit

  1. Mar 18, 2008 #1
    I've attached the problem in this post, so that's way yall can see the problem and picture easily.

    3. The attempt at a solution

    what is this signal [tex]\sum[/tex] means in the problem?
    THe problem said they find the ammeter in the cirucuit read 2A, I just wonder is it the total current?
    If i set up I = I1 + I2, then in loop 1 (top loop) I can use I and I1 to; and in loop 2(bottom loop) I can use I and I2 in order to find the currents. Is it correct? Please give me a hint. Thank you!!
    Last edited: Mar 18, 2008
  2. jcsd
  3. Mar 18, 2008 #2


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    Homework Helper

    The symbol is a capital Sigma, it generally means sum of ( ie add them all up )
    ps - You don't seem to have attached the picture properly
  4. Mar 22, 2008 #3
    Thanks. I did fixed the picture. Can anyone please help me out?
  5. Mar 22, 2008 #4
    define the potential to the point to the right of the ammeter to be 0.
    call the potential to the left of th 5 ohm resistance U.
    What must U be to make the current through the ammeter equal to 2A?
    Once you have U you can calculate I_1 and the use kirchhof's current law to get I_2
  6. Mar 22, 2008 #5
    Go around the bottom loop and go around the top loop using Kirchoff's loop law, then find I3 through the ammeter in terms of I1 and I2. 3 equations and 3 unknowns.
  7. Aug 8, 2008 #6
    I want answer for questions, wuold you help mme?
  8. Aug 8, 2008 #7


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    Unfortunately no one can give you the answer, per PF rules. Show your work and we'll help you if you have problems.
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