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Homework Help: Quick RC circuit question

  1. Nov 3, 2008 #1
    In the equation I= Imax * e^(-t/RC)

    When do you use E/R for Imax
    and when do you use Qmax / RC

    I have seen them used interchangeably in discharging problems and in charging problems. Are there any guidelines to use one for one type of problem and the other for another type?
    To me they seem to be equal, so does it even matter which one is used?

  2. jcsd
  3. Nov 3, 2008 #2


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    Use that when you know either the final voltage (charging up a cap) or initial voltage (capacitor is discharged through a resistor).

    ... and use that when you know either the initial or final charge.

    It depends just what information is given, either voltage or charge. And yes, they are pretty much equivalent expressions.
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