inductor

Discussion in 'Homework Help' started by acw_wellsy, Oct 2, 2006.

  1. acw_wellsy

    Thread Starter New Member

    Oct 1, 2006
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    an inductor is connected to a sinusoidal voltage with amplitude of 120 V. a peak current of 3.0 A appears in the inductor.
    A) what is the maximum current if the frequency of the applied voltage is doubled?
    B) what is the inductive reactance at each of the two frequencies?

    this has got me stumped if you dont know the inductance or frequency...
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,582
    770

    But you can do the maths, get reactance out of 120V and 3Ap (hint: what is the efficient value of current?), and then you can count the inductance, if you want.
    But because the question is not inductance, but reactance, you should be able to get the answers easily.
    BTW this example assumes ideal inductor, eg. with no resistance.
     
  3. richbrune

    Senior Member

    Oct 28, 2005
    106
    0
    inductor is connected to a sinusoidal voltage with amplitude of 120 V. a peak current of 3.0 A appears in the inductor." tells only that the total impedence is V/I or 120/3 or 40 ohms. That seems to imply that it could be a zero Henry coil, and all of the 40 ohms is resistance. Double the frequency still gives 40 ohms, thus 3 amps. Or it could be some kind of larger inductor, and increase of frequency then gives attenuation and phase shift, right? Inductive reactance is: x = 6.28FL or 6.28 times frequency times inductance. So a 6.369 H coil at 1 HZ gives 40 Ohms thus 3 amps, but the same 6.369H coil at 2 HZ gives 80 Ohms, thus 1.5 Amps. Is this all right?
     
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