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Gee Wiz
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Homework Statement
A circuit is constructed with four resistors, one capacitor, one battery and a switch as shown. The values for the resistors are: R1 = R2 = 22 Ω, R3 = 91 Ω and R4 = 129 Ω. The capacitance is C = 40 μF and the battery voltage is V = 12 V. The positive terminal of the battery is indicated with a + sign.( picture: https://www.smartphysics.com/Content/Media/Images/EM/11/h11_RC_time.png )
After the switch has been closed for a very long time, it is then opened. What is Q(topen), the charge on the capacitor at a time topen = 790 μs after the switch was opened?
Homework Equations
Q(t)=Qmax(1-e^(-t/rc))
The Attempt at a Solution
I found earlier that the Q at infinity is 180.496uC. I assume that would be my Qmax. My t would be 790us. I think I am messing up getting rc. My final answer comes out as negative each time. (clearly not correct)
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