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Homework Help: Find the maximum AC current flowing through the generator.

  1. Apr 27, 2009 #1
    QUESTION 10***
    A generator with output voltage ε(t) = εmax cos (ωt) is connected to the primary of a transformer. A resistor is connected to the transformer secondary. The transformer has an iron core with N1 turns on the primary and N2 turns on the secondary. Assume that the transformer is ideal and dissipates no energy.

    Find the maximum AC current flowing through the generator.

    http://online.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys212/oldexams/exam3/fa07/fig10b.gif [Broken]

    http://online.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?courses/phys212/oldexams/exam3/fa07/fig10a.gif [Broken]

    V2 = (N2 / N1) V1. <--- equation for transformer

    V2 is the voltage across the second coil, and V1 is the generator voltage, which is Emax.
    So to solve for the max AC current, I divide V2 by R, which would yield choice A, but the answer is B, can someone explain what I did wrong?
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Apr 28, 2009 #2


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    Homework Helper

    Re: Transformer

    They have asked Imax in primary circuit.
    V2 = (N2 / N1) V1.
    Next input power = outputpower.
    So V2 I2 = V1I1
    I1 = (V2/V1)I2.. Substitute the values of V2/V1 and I2 to get the result.
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