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peaceandlove
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Homework Statement
A 3 µF capacitor is charged to 76 V and is then connected across a 698 Ω resistor. (a) What is the initial charge on the capacitor? Answer in units of µC. (b) What is the initial current just after the capacitor is connected to the resistor? Answer in units of A. (c) What is the time constant of this circuit? Answer in units of ms. (d) How much charge is on the capacitor after 5.122 ms? Answer in units of µC.
Homework Equations
1) Q= CV
2) I= V/R
3) (TC) = RC
4) V = (V_0)(1-(e^(-t/RC)))
The Attempt at a Solution
a) Q=CV; Q=3 uF * 76 V; Q=228 uC
b) I = V/R; I=76 V/ 698 Ohm; I=0.109 A
c) TimeConstant TC=RC; TC=698 * 3 uF; TC=2.094 mSec
However, I can't figure out (d). I used equation 4 to figure out the voltage at 5.122 ms (=0.005122 s) and then plugged in the numbers to equation 1. I got 227.44298 µC, but that value is incorrect.