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Homework Help: Help with a circuit!

  1. Oct 1, 2007 #1
    Hello, all. I know they are very smart people on this site, that's why I'm posting here. I'm on my first year of college, and I really need help with a problem(it's worth half a grade!!) I'm sure, it's a pretty simple exercise for you all, but I do have trouble solving it. So, please, if you can be so kind, help me, please!

    Here's the link to the exercise;

    http://www.physics.uprm.edu/~mark/courses/FISI3172_I2007/OptionalProblem.pdf [Broken]

    Here it is. So, the current is 0, am I supposed to sum the first two resistances in series(1,2), then the other two(3,4) in series, then (12,34) on paralell?

    I'm not sure, I'm not good at this right now, please help me, and be detailed, please!

    Thanks a lot, if you help me. Bye

    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Oct 1, 2007 #2


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    Staff: Mentor

    They are asking for a more intuitive answer than just combining the resistors. If the current I=0, what can you say about the two node voltages (one between R1, R2, and the other node between R3, R4)? And then, what can you say about the ratio of R1/R2 versus R3/R4?
  4. Oct 1, 2007 #3
    I apologize, because I posted in a wrong section. Anyway, what I've gotten so far;


    Two voltage dividers-ratios must be the same for zero current to flow.

    Could that be the answer to the question?
  5. Oct 1, 2007 #4


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    Staff: Mentor

    Very good. That is what I would have put for the answer. Welcome to the PF, BTW.
  6. Oct 1, 2007 #5
    Awesome, thanks man. Hope I can see you around here sometimes. See ya.
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