(adsbygoogle = window.adsbygoogle || []).push({}); LC circut: Charge on a capacitor at a given time

1. The problem statement, all variables and given/known data

I don’t have a pic but a simple loop circuit is constructes with 2 capacitors c1 and c2 in series, after the capacitors in an inductor also in series, and the wire continues back into c1. The values for the capacitors are: C1 = 409 μF and C2 = 294 μF. The inductance is L = 397 mH. At time t =0, the current through the inductor has its maximum value IL(0) = 64 mA and it has the direction shown (CW) from capacitors on left to inductor on right.

What is Q1(t1), the charge on the capacitor C1 at time t = t1 = 30.2 ms?

2. Relevant equations

Q(t)=Qmax*cos(Omega*t+phase angle)

this equation gives the charge on a capacitor as a function of time

3. The attempt at a solution

Using the equivalent capacitance I found the the angular frequency omega was 121.352 rad/sec which is correct, however when trying to find q max I get a bit lost, they tell me that the current through the inductor has its maximum value IL(0) = 64 mA, so I tried to use energy equations

U capacitor =1/2 c*v^2 and U inductor= ½ L*i^2

I found that the total max potential energy in the inductor is 8.135e-4

I don’t exactly know where to go from here. I can solve for the V and thus Q in the equivalent capacitor but that doesn’t exactly help me since I need the Q through only c1

Am I on the right track or did I go wrong somewhere?

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# Homework Help: LC circut

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