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Homework Help: Secondary voltage and current?

  1. Dec 20, 2009 #1
    Secondary voltage and current??

    1. The problem statement, all variables and given/known data
    A load resistor is placed across the secondary terminals of a step-down transformer with a turn ratio of 4:1. If the primary voltage and current are 120V and 1A., What will be the secondary voltage and current? Assume 100% efficiency.

    2. Relevant equations

    Ns/Np = Vs/Vp = Ip/Is

    3. The attempt at a solution
    Ns should be 4,,right??
    but If Ns = 4..then, I don't get the right answer...
    why is Np 4?? Np is primary isnt it??

    The answers were 30v and 4A.
  2. jcsd
  3. Dec 20, 2009 #2


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    Science Advisor
    Homework Helper

    Hi SAT2400! :smile:

    It's a step-down transformer, and you're told the ratio is 4:1, so Ns/Np = 1/4. :wink:
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