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Circuit problem

  1. Aug 12, 2009 #1
    1. The problem statement, all variables and given/known data

    I've this circuit:
    -----Resistor (100000 ohms)---/ (switch) -------
    | | |A
    Battery Capacitor Inductor
    | | |
    | | Resistor2
    At points A, B, they are connected to a oscilloscope. The inductor/resistor2 combination have an inductance of 0.01 henry. When the switch is closed, the oscillatorscope is triggered.

    I think that you'd have 2 currents, I1 and I2, if I1 flows clockwise through the large resistor and then I2 flows counterclockwise through the second loop of the circuit. I think you can isolate the loop of I2 since resistance in the first loop resistor is so large (100000 ohms). So then I can just do C is approximately 1/w^2L, where L is the inductance and w is the angular frequency (which I am supposed to determine on a separate chart). But I am asked how I am supposed to find an expression for the charge on the capacitor? I know that Q = CV. So then V across this LResistor2 combination is the same as voltage across C.
    2. Relevant equations
    Q = CV
    I = dQ/dt
    V = LdI/dt + RI
    3. The attempt at a solution
    do I have:
    [tex]V = \frac{dI_{2}}{dt} + R_{2}I_{2}[/tex], which is
    [tex]Q/C=\frac{d^{2}Q}{dt^{2}} + R_{2}\frac{dQ}{dt}[/tex]
    and then
    [tex]V = R_{1}I_{1} + Q/C[/tex]?
    Actually, not sure what to do about the rest? Thanks.
  2. jcsd
  3. Aug 12, 2009 #2


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    Science Advisor
    Homework Helper
    Gold Member

    Your circuit diagram did not come through in any way that can be interpreted. Also, it is not clear what you are asked to find.
  4. Aug 12, 2009 #3
    Oh sorry, but never mind. I will just use old Kirchoff's Laws and write down the expression fot voltage across the 2 loops, and then derive the answer that way. Thanks anyway.
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