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Homework Help: Finding Resistance in RC Circuit

  1. Jan 29, 2017 #1
    1. The problem statement, all variables and given/known data
    In a simple RC circuit the current as a function of time behaves in the following manner:

    I(5s) = 8.823
    I(10s) = 7.788
    I(20) = 6.065
    I(30) = 4.724
    I(40) = 3.679
    I(50) = 2.865
    I(60) = 2.231
    I(70) = 1.738
    I(80) = 1.353
    I(90) = 1.054
    I(100) = 0.821
    I(110) = 0.639

    Assuming that the capacitance C = 837 nF, what is the resistance R (in MΩ)?

    2. Relevant equations

    3. The attempt at a solution
    I have attempted this many different times. I know that the RC constant is equal to the resistance times the capacitance but I'm having trouble finding the RC constant and don't really have any idea where to start.
  2. jcsd
  3. Jan 29, 2017 #2


    User Avatar
    Homework Helper
    Gold Member

    Hi Matt! Welcome to PF!
    You should show your attempt here.
    Is the capacitor charging or discharging?
    What will be the equation of the current? How many unknowns will it have?
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