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Finding current across capacitor

  1. Jul 22, 2008 #1
    1. The problem statement, all variables and given/known data
    An ac generator with a frequency of 30.0Hz and an rms voltage of 12.0V is connected to a 45.5uF capacitor. a) what is the maximum current in this circuit? b) what is the current in the circuit when the voltage across the capacitor is 5.25V and increasing? c) what is the current in the circuit when the voltage across the capacitor is 5.25V and decreasing?


    2. Relevant equations
    Irms=Vrms/Xc Xc=1/2pi(frequency)(capacitor) Io=Irms X square root of 2


    3. The attempt at a solution

    a) I first solved for Xc and got 116.6Ohms and Irms=12V/116.6Ohms=0.102A
    Io=0.102X square root of 2=0.146A
    I think i have this part right, but check it for me. thanks.

    b) V=5.25V my attempt was to just divide by my Xc, but that does not come out right. the answer is the book is 138mA.

    c) -138mA

    thanks for the help
     
  2. jcsd
  3. Jul 24, 2008 #2
    Part a) is good. I think you did parts b and c right too, is your book known to have errors?
     
  4. Jul 24, 2008 #3
    very very rarely will it have a wrong answer...
     
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