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Homework Help: RLC Circuit (with variable frequency!)

  1. Jan 5, 2010 #1
    1. The problem statement, all variables and given/known data

    Find the frequency at which the circuit becomes purely resistive and calculate the effective resistance.

    Here is the circuit with the given solution-

    23qgif.jpg

    The trouble is, whilst the solution is simple enough, there are many places to go wrong, and the whole process is time comsuming. I've managed to simplify a few other answers given in this answer booklet, but for this one, i can't find an easier method.

    Any ideas? I can't find a similar example in Hughes.

    Thanks,
    Josh.
     
  2. jcsd
  3. Jan 5, 2010 #2

    ehild

    User Avatar
    Homework Helper

    If Z is real so is 1/Z.

    [tex]\frac{1}{Z}=\frac{R-j\omega L}{R^2+(\omega L)^2}+j\omega C=\frac{R}{R^2+(\omega L)^2}+j\omega( C-\frac{ L}{R^2+(\omega L)^2})[/tex]

    ehild
     
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