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Transformer qs, find turns ration & primary current

  1. May 17, 2010 #1
    1. The problem statement, all variables and given/known data
    A step up transformer is designed to operate from a 12V supply and to deliver energy at 240V. If the secondary winding is connected to a 60W, 240 V lamp, determine:

    a) the turns ratio of the transformer
    b) the primary current



    2. Relevant equations

    P primary = P seconary

    Vp/Vs = Is/Ip = Np/Ns

    3. The attempt at a solution
    -ok...well, I don't know how to do this at all, my textbook only had really straight forward questions where the info for primary and secondary was directly given...please help
     
  2. jcsd
  3. May 17, 2010 #2

    kuruman

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    First question to answer: Is this a step-up or step-down transformer?
     
  4. May 17, 2010 #3

    -it's a step up

    that means Vp is less than Vs, but Ip is greater than Is


    i don't know how to identify the P, Vp, Vs from the info...
     
  5. May 17, 2010 #4

    kuruman

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    What is hooked up to the power supply is the primary. So what is Vp?
     
  6. May 17, 2010 #5
    so Vp is 12V and than I guess Vs is 240V and P is 60W.
     
  7. May 17, 2010 #6

    kuruman

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    Can you find the turns ratio now? What about the current in the primary?
     
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