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Homework Help: Energy in Circuit between load

  1. Aug 2, 2007 #1
    1. The problem statement, all variables and given/known data
    All components arranged parallel,

    voltage source =10sqrt(2)cos(2000t)
    10 ohm resistor, 10mH inductor, 15 microF
    How much energy is exchanged between the source and the load? (book answer: 0.0962J) Between the capacitor and the inductor? (0.144J)

    But I think the book answer made a mistake in getting Z_eq which gave the wrong anwer. I think they left Z_eq invert and used it as Z_eq in calculation

    2. Relevant equations
    I_p = V_p / Z_eq
    S =0.5 (V_P) (I_P*) -> giving a complex solution, where the real is P and im is Q

    Between source and load: W = Q/omega
    Energy in inductor W = (0.5)( L )(I_P)^2
    energy in capacitor W = (.5) (C) (V_p)^2

    3. The attempt at a solution

    Find the Z_eq by adding the admittance of the components, then invert it giving 9.8 with degree 11.3

    Find I with the equation above 1.02 sqrt(2) degree -11.3

    Find S giving Real(10) + Im(2) -> p=10 Q = 2

    Energy between load and source: using omega = 2000 -> W = 2/1000 = 0.001

    Energy between capacitor and inductor: I think it should be the energy of the inductor plus capacitor
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Aug 3, 2007 #2
    Is the load supposed to be the whole network, the resistor, or something else? Also, I think you are correct that it wants the energy of the inductor plus the capacitor.
  4. Aug 3, 2007 #3
    Yes, The load consist of the resister, inductor and capacitor.
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