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Homework Help: Transformer problem, Please Help

  1. Apr 13, 2013 #1
    Transformer problem, Please Help!!!

    Please help with this problem.

    A transformer consists of 300 primary windings and 804 secondary windings.
    a) If the potential difference across the primary coil is 21.0 , what is the voltage across the secondary coil ?
    Found this part, Vs = 56.3 V

    b) If the potential difference across the primary coil is 21.0 V , what is the effective load resistance of the secondary coil if it is connected across a 145 Ohms resistor?

    This part I am not getting. Is it saying that 145 Ohms is Rp (Resistance of the primary coil) ??, or there are more than one resistors for the secondary coil and I need to find the Req. Please help!!!
    1. The problem statement, all variables and given/known data
  2. jcsd
  3. Apr 13, 2013 #2

    rude man

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    Homework Helper
    Gold Member

    Probably they mean what resistance is reflected back to the primary winding. In other words, what resistance does the 21V source see?

    You can deduce the answer from an energy-conservation argument.
  4. Apr 14, 2013 #3
    Thank you!
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