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Homework Help: What is the capacitance of this device?

  1. Jan 22, 2006 #1
    An automatic external defibrillator (AED) delivers 125J of energy at a voltage of 1050V. What is the capacitance of this device?

    Possible Ans
    Capacitance is charge / voltage.
    We have the voltage so how can you get a value for charge?
  2. jcsd
  3. Jan 22, 2006 #2


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    Homework Helper

    Do you know the formula for energy stored in a capacitor?
  4. Jan 22, 2006 #3
    oh ok,
    so U = 0.5qV
    so q = 0.238 V

    Fill in to capacitance formula and i got 2.267 x 10^-4 C/V
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