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Electrical circuit related problem

  1. Sep 16, 2013 #1
    1. The problem statement, all variables and given/known data

    Determine the value of the voltage Vx
    across the 3A current source.

    2. Relevant equations



    3. The attempt at a solution
    I am really confused about how to do it. What I thought of is to find the voltage across the 4 ohm resistance which is 12 V. I though of subtracting that from the power sources.

    But I am not sure which power source should be positive and which one should be negative?
    Should I just assume the bigger 6V to be positive just because it is the bigger power source?
    I might be completely wrong on this one. So please help me. This is not really a homework problem, this is in one of my practice tests, so I would appreciate any proper explanation I can get, rather than vague hints.
    Thank you.
     

    Attached Files:

  2. jcsd
  3. Sep 16, 2013 #2
    Oh and please look at the attachment for the diagram
     
  4. Sep 17, 2013 #3

    gneill

    User Avatar

    Staff: Mentor

    Sure, sounds like a good idea. Use KVL around the left loop.
    The voltage sources are labeled with their polarities so no need to guess! Just do a "KVL walk" around the loop in either direction and sum up the potential changes as you go. The math will take care of itself.
     
  5. Sep 17, 2013 #4
    ya u r right. Got it and thanks a lot.
     
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