1. The problem statement, all variables and given/known data A charged capacitor is connected to an ideal inductor to form an LC circuit with a frequency of oscillation f = 1.6 Hz. At time t = 0 the capacitor is fully charged. At a given instant later the charge on the capacitor is measured to be 3.0 μC and the current in the circuit is equal to 75 μA. What is the maximum charge of the capacitor? 2. Relevant equations q = Qcos(ωt) i = -ωQsin(ωt) 3. The attempt at a solution Alright, this problem has been driving me nuts. I'm honestly not sure how to go about this one, and I think there are some errors in the steps I took, but here's what I've done so far. Since we're given the frequency, I solved for ω. ω=2pi*f = 10.05 rad. Then, I used dq/dt to find the time. Now, I feel weird about this step, since dq/dt is the rate of change of the charge, but essentially, I thought of it as i = q/t (I believe I made a huge error in making this assumption, but I wasn't sure how else to go about this...) Substituting, I found t = q/i = .04s. And then I used both of the above equations to attempt to find a value for Q. Both give me two different numbers, both of which are incorrect. Conceptually, I understand what's going on here. Initially, the capacitor is fully charged. When there's a current running through the circuit and a charge on the capacitor, the capacitor is in the process of discharging (or charging, considering we don't know the specifics). I just don't quite see how to go about arriving at the correct answer. I'm pretty sure my method of solving for t is absolutely wrong, but I'm stumped! Any help would be greatly appreciated!