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Homework Help: AC Current

  1. Aug 1, 2007 #1
    1. The problem statement, all variables and given/known data
    A circuit contains only 0.197 H inductor. An AC voltage of peak value 166 V and frequency 60.5 Hz is applied to the circuit. When the voltage is 166 V, what is AC current? Answer in units of A.

    2. Relevant equations

    3. The attempt at a solution

    we know that inductive reactance is XL= ωL
    AC voltage peak value IS V = 166 Volts
    then AC current is I = V/XL
    ω = 2π(FREQUENCY) = 2π(60.5) RAD/SEC
    L = INDUCTANCE = 0.197 H
    THEN I = 166/ 2π(60.5)*0.197 = 2.22 A

    The answer is wrong, could someone tell me what I'm doing wrong? Thank you!
  2. jcsd
  3. Aug 2, 2007 #2
    You have obtained peak AC current, because you used peak voltage in Ohm's law. Probably you're asked to find effective current.
  4. Aug 2, 2007 #3


    User Avatar

    Staff: Mentor

    Remember that V = L dI/dt, so there is a phase shift between voltage and current in an inductor. Do you know how many degrees the current waveform is off of the voltage excitation waveform, and in which direction?
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