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Homework Help: Find the impedance and ω for (R and L in series, & C in || )

  1. Oct 2, 2016 #1
    1. The problem statement, all variables and given/known data
    Find the impedance (Z) of the circuit in the shown figure (R and L in series, and C in parallel with them). A circuit is said to be in resonance if Z is real, find ω in terms of R, L, and C?

    2. Relevant equations
    VR= RIeiωt
    VL= LiωIeiωt
    VC= (Ieiωt)/(iωc)

    What I mean by I is I (not) H didn't know how to write it and i imaginary number, I hope the I wrote the equations clearly.

    3. The attempt at a solution
    What I think about is:
    1. Find Z.
    2. Put Z in term of x+iy.
    3. If Z is real then y=0.
    4. find ω from y=0.

    If that correct I should find Z, but I'm not sure about it.
    first I found Zseries for R & L = R+iωL
    then Z = Zseries || ZC
    Am I right? or there are some specific formulas as if all R, L & C are in series?
  2. jcsd
  3. Oct 2, 2016 #2


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  4. Oct 2, 2016 #3


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    To avoid confusion with current, imaginary number 'i' in mathematics is denoted by 'j' in electrical circuit analysis. So the reactances become jXL and -jXc (Note 1/j= -j).
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