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Homework Help: Time needed to reduce charge of a capacitor

  1. Oct 18, 2009 #1
    1. The problem statement, all variables and given/known data
    A 20 uF capacitor initially charged to 20 uC is discharged through a 1.0 kOlhms resistor. How long does it take to reduce the capacitor's charge to 8.0 uC?




    2. Relevant equations

    I=dQ/dt



    3. The attempt at a solution

    I know that dQ = 12 uC. What I can't figure out is how to get I from the given data. I'm assuming I need to use the 20 uF along with the resistance to find the I but I don't know how that can be done. I appreciate any help, thanks!
     
  2. jcsd
  3. Oct 18, 2009 #2

    OmCheeto

    User Avatar
    Gold Member

    I think you need more relevant equations. Do you know what the initial voltage is across the capacitor?
     
  4. Oct 18, 2009 #3
    I figured it out
     
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