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Homework Help: Question regarding alternating current

  1. Jan 12, 2005 #1
    When an a.c. flows in a resistor,the mean power dissipated is P.If the frequency of the a.c. is doubled with the same value of peak voltage,what id the average power dissipated now ?

    My solution :

    P = (I_rms)^2 R

    I assume that as the peak voltage remains the same and the mean power value doesn't influenced by the frequency of the a.c. , so the mean power remains the same, that is P.

    Is my assumption right ?I hope that someone will help me figure out.Do comment if I have any error in my assumption.Thanks for anybody that spend some time on this question.
  2. jcsd
  3. Jan 12, 2005 #2


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    The root mean square voltage is derived from mean power considerations. Hence it is independent of the frequency. As long as the peak voltage is the same, the r.m.s. voltage is the same, and hence the mean power output is the same.
  4. Jan 12, 2005 #3

    Andrew Mason

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    Science Advisor
    Homework Helper

    Your assumption is correct, in a circuit with no inductance. Inductive reactance, which limits current, is frequency dependent.

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