can you help me please ?

Discussion in 'Homework Help' started by KFUPM University, Apr 28, 2011.

  1. KFUPM University

    Thread Starter New Member

    Apr 28, 2011
    9
    0
    hi guys , I am having difficulty in solving this circuit by transformation

    can you show me the steps and how to find Vx(voltage)
     
  2. jegues

    Well-Known Member

    Sep 13, 2010
    735
    43
    Start off by transforming the two voltage sources and series resistances on the left hand side of the circuit into current sources with parallel resistances.

    After doing so you should be able to make a parallel combination of the resistances and current sources.

    That should be enough to get you started!
     
  3. KFUPM University

    Thread Starter New Member

    Apr 28, 2011
    9
    0
    i tried but i didn't find the right answer (48V)

    could you explain more plz
     
  4. jegues

    Well-Known Member

    Sep 13, 2010
    735
    43
    If you show us your attempt it makes it alot easier for us to help you.

    I'll get you started with the leftmost voltage source and resistance.

    Applying ohms law we would see a current source of the value,

    I = \frac{V}{R} = \frac{120V}{20\Omega} = 6A

    The value of the parallel resistance for the transformed voltage source will be identical to its previous(before being transformed) series resistance.
     
  5. jegues

    Well-Known Member

    Sep 13, 2010
    735
    43
    Also, there may be a mistake in the figure you've posted. Usually the positive terminal of a DC voltage source is on the end with the wider "line".

    In your figure it seems to be the opposite.
     
  6. KFUPM University

    Thread Starter New Member

    Apr 28, 2011
    9
    0
    thank you my friend i I appreciate all the work you have put in

    when i converted it to be 2 resistances and voltage source i used VDR

    thx again
     
  7. steveb

    Senior Member

    Jul 3, 2008
    2,433
    469
    Are you saying the correct answer is 48V, or did you get 48V?
     
  8. KFUPM University

    Thread Starter New Member

    Apr 28, 2011
    9
    0
    yes it is 48v
    also as you said the signs should be opposite
     
  9. steveb

    Senior Member

    Jul 3, 2008
    2,433
    469
    So, what did you get for your answer?

    I ask because I did it out by two methods. Both answers agreed but it came out less than 48V.

    I'm curious if you got the same answer I did.

    First I did it using source transformation, and then I checked it using circuit equations. Perhaps there is an error in the schematic, as mentioned above.
     
  10. KFUPM University

    Thread Starter New Member

    Apr 28, 2011
    9
    0
    this my final answer it is ok i check solution same final answer

    look at attachment
     
  11. steveb

    Senior Member

    Jul 3, 2008
    2,433
    469
    OK. I just noticed that if you assume that V1 us defined backwards and V2 is correct, the answer is 48v.

    Try it that way. EDIT: Ok I see that you did it that way above. Good!
     
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