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Homework Help: Charge through Inductor

  1. Oct 22, 2009 #1
    1. The problem statement, all variables and given/known data

    A selfinduced emf in a solenoid of inductance L changes in time as E = E.e^-kt. Find the total charge that passes through the solenoid, assuming the charge is finite.

    2. Relevant equations
    E = LdI/dt
    U = 1/2LI^2
    I = dQ/dt

    3. The attempt at a solution
    I'm pretty stumped by this one, honestly. I thought I might have to use I(t) = E/R(1 - e^-Rt/L) somehow. I don't really understand how the emf is changing in time?
  2. jcsd
  3. Oct 22, 2009 #2


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    Homework Helper

    Well I am not sure if the Es in E=E.e-kt are the same but you can do this

    L(dI/dt)=Ee-kt and then do something similar with dQ/dt
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