http://www.flickr.com/photos/84781786@N0… (when the switch is flipped the other way to get this):
http://i43.tinypic.com/iw56bk.jpg
generating an expression for Vc(t) and then ic(t) for current through R3 using R1,2,3 Vg, and C.
I get that the
is Vc(t) = Vg(e)^(-t/(RC))
and
ic(t)=-Vg/(R)e^(-t/(RC))
to find the V across the capacitor we know that R2 is parallel to R3 (to find Req). then is the RC value simply C*(R2*R3/(R2+R3))? where does R1 even come into the equation?
i'm not sure what i'm doing wrong
http://i43.tinypic.com/iw56bk.jpg
generating an expression for Vc(t) and then ic(t) for current through R3 using R1,2,3 Vg, and C.
I get that the
is Vc(t) = Vg(e)^(-t/(RC))
and
ic(t)=-Vg/(R)e^(-t/(RC))
to find the V across the capacitor we know that R2 is parallel to R3 (to find Req). then is the RC value simply C*(R2*R3/(R2+R3))? where does R1 even come into the equation?
i'm not sure what i'm doing wrong
-
R1 comes into it because before the switch moves to the right the voltage on C is
Vinitial = Vg*R2/(R1 + R2)
...*not* just Vg.
After the switch moves to the right, C discharges through the parallel combination of R2 and R3 (as you said). Call that parallel combination Rp.
Vc = Vinitial*e^(-t/C*Rp)
Current in R3 = Vc/R3
Vinitial = Vg*R2/(R1 + R2)
...*not* just Vg.
After the switch moves to the right, C discharges through the parallel combination of R2 and R3 (as you said). Call that parallel combination Rp.
Vc = Vinitial*e^(-t/C*Rp)
Current in R3 = Vc/R3