Question Regarding Capacitance And Inductance

  1. Mar 25, 2014 #1
    Hi there,

    I'm doing a home study course including a section on dynamic fields and waves. I am trying to understand how to find capacitance using initial charge, inductance and energy.

    From a previous section, I know I can find the maximum current using Um=1/2 LI2

    However, I can't see how to find the capacitance. Can anyone point me in the right direction please.

    Many thanks

  2. jcsd
  3. Mar 25, 2014 #2


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    Staff: Mentor

    What does the circuit look like? Can you upload a PDF?
  4. Mar 25, 2014 #3


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    Science Advisor

    Knowing the initial charge and energy should be enough to compute capacitance.

    From the definition of capacitance, C = Q / V
    therefore V = Q / C.

    We know that the energy stored in a capacitor is, E = ½ C V^2

    therefore E = ½ C (Q/C)^2
    so E = ½ Q^2 / C
    hence C = ½ Q^2 / E.
  5. Mar 25, 2014 #4
    Its a simple circuit with just a capacitor and a solenoid, nothing else
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