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Homework Help: Energy stored in a RLC circuit

  1. Apr 20, 2008 #1
    1. The problem statement, all variables and given/known data

    A 21.0 \mu F capacitor is charged by a 160.0-{\rm V} power supply, then disconnected from the power and connected in series with a 0.220-{\rm mH} inductor.

    Calculate the energy stored in the capacitor at time t = 0{\rm{ ms}} (the moment of connection with the inductor).

    Calculate the energy stored in the inductor at t = 1.30 ms.

    2. Relevant equations

    i=-omegaQsin(omega*t)

    and U=.5LI^2

    I need to either find charge q or a resistance value to find I with and I'm stuck..
     
  2. jcsd
  3. Apr 21, 2008 #2

    alphysicist

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    Homework Helper

    Hi danbone87,

    The way the capacitor is initially connected by itself to the battery will give you its initaial Q value.

    If I'm reading the problem correctly, there is no resistor; just a capacitor connected to an inductor.
     
  4. Dec 13, 2011 #3
    A 21.0 \mu F capacitor is charged by a 160.0-{\rm V} power supply, then disconnected from the power and connected in series with a 0.220-{\rm mH} inductor.

    Calculate the energy stored in the capacitor at time t = 0{\rm{ ms}} (the moment of connection with the inductor).

    Calculate the energy stored in the inductor at t = 1.30 ms.


    ans= q=cv=22u*160m gives u charge
    energy=.5*22u*160m*160m=1/2(c*v*v)
    now
    VL=Ldi/dt
     
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