# RC Circuit Transient Response

by dudforreal
Tags: circuit, transient
 Mentor P: 10,804 Gotta go catch some zZ's now. I'll check back in the morning (my morning, that is).
 P: 116 I think that my answer is wrong because when I used this equation on a different question with the same circuit with the voltage source being 4V, R1 = 1600, R = 2000 and C = 10n the answer I got was 0.798V but the correct answer is 1.4239V.
 Mentor P: 10,804 Good morning. (*YAWN*) I took another look at the problem. A small correction is required to the time response formula. This time the exponential is starting at zero and heading towards a final value that's equal to the Thevenin voltage of the resistor network. So the form is: $$V_o(t) = V_{th} \left(1 - e^{-t/\tau} \right)$$ Regarding your "different question with the same circuit", apply the above suggested formula and recheck your result -- also check to see if the time t1 to be plugged in is the same for both problems.
 P: 116 ok cool i got the answer. Now for the second part of the question with the switch between the resistor and the voltage source, my answer for the time before and after 0 as 0V and it is going to -5(7500/17500) = -2.143V.
Mentor
P: 10,804
 Quote by dudforreal ok cool i got the answer. Now for the second part of the question with the switch between the resistor and the voltage source, my answer for the time before and after 0 as 0V and it is going to -5(7500/17500) = -2.143V.
Yes, that's what I see for that circuit.
 P: 116 ok thanks i got the answer

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