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Basic farad question

  1. Aug 6, 2009 #1
    Tolerate my ignorance wise ones.

    I'm trying to get a simple common sense explanation to figure out how much current I can get from a capacitor bank and for how long.

    I read that 1 Farad is 1 Ampere second per Volt. So does this mean that a 1 farad capacitor charged with 1V will dissipate its 1 amp charge in 1 second (if shorted). Is this mostly correct?

    So if I charged this 1 Farad cap with 12V does that mean it has 12 Amps at 12V because its “per volt”?

    Also if I’m creating a capacitor bank I want them in parallel if I want all the power to come out at once right?
     
  2. jcsd
  3. Aug 6, 2009 #2

    berkeman

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    Staff: Mentor

    Welcome to the PF. Couple basic equations you can use:

    Q = C * V
    the charge Q [Coulombs] is equal to the capacitance [Farads] * voltage [Volts]

    I = dQ / dt
    the current I [Amps] is equal to the amount of charge dQ [Coulombs] passing a point in a given time dt [seconds]

    You should be able to use these to start to figure out how much current you can get from capacitors for some time period. However, you don't generally short the output of capacitors. You apply some load resistance R, and the capacitor discharges with an exponentially decreasing voltage and current characteristic. Remember the fundamental equation:

    V = I * R
    voltage [Volts] equals the current I [Amps] * resistance R [Ohms]
     
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