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Homework Help: Potential Change in a Circuit Diagram

  1. Mar 4, 2008 #1
    [SOLVED] Potential Change in a Circuit Diagram

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

    If the potential at point P is 400 V, what is the potential at point Q?

    2. Relevant equations
    Ohm's Law: deltaV=iR
    Probably the fact that the sum of changes in potential in a loop of any circuit must be zero.

    3. The attempt at a solution
    Not real sure on this problem. I tried this:
    150V - 2.0i - 3.0i - 50V = 0V and found i to be 20A.

    I'm kind of puzzled and can't seem to relate the material in the textbook to this problem. Where does the 400V potential come into play? Thanks for your help!
    Last edited by a moderator: Apr 23, 2017
  2. jcsd
  3. Mar 4, 2008 #2
    I'm still not really sure this is the proper way to approach the problem but apparently the solution is correct. Here's what I did:

    Used 20A from above.

    400V - 50V - 3.0ohms * 20A = 290V
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