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Need help on transformers

  1. Jul 16, 2008 #1
    1. The problem statement, all variables and given/known data

    http://img169.imageshack.us/img169/8502/73860646mw1.jpg [Broken]

    R3= 10.0Ω
    IR1= 2.0A

    Prove that Vpri =30( 10R1+R1R2+10R2)/R2

    2. Relevant equations

    3. The attempt at a solution
    Current across R2= 2xR1/R2
    Current across R3= 2R1/R2 +2A
    Total Voltage in sec coil= [2R1/R2 +2] x10 + 2R1
    = 20R1+20+2R1R2/R2

    Im stuck here currently=( any help?
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Jul 18, 2008 #2


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    Is this the only information given? Are you sure the 2A current is through R1?

    We describe current as going through an element (such as a resistor), rather than across it. Voltage, on the other hand, is measured across an element.
  4. Jul 18, 2008 #3
    Yea the current through R1 is 2.0A. I already gt the answer=) apprently the teacher forgot to give the turns ratio for the qn. Thanks anyways=)
  5. Jul 18, 2008 #4


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    I thought so, I was just about to add, unless this were an isolation transformer, I would expect a ratio of turns (N1:N2), voltage (Vp:Vs), or current (Ip:Is) to be given.

    What was the turns ratio? (I'd like to solve this one too).
  6. Jul 20, 2008 #5
    Oh the turns ratio was 15:1
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