1. The problem statement, all variables and given/known data "The switch in the circuit in the figure has been closed for a long time and is opened at t = 0. Find i(50 ms)." I attached an image of the circuit below. 2. Relevant equations KVL: Ri + q(t)/C - q(0)/C + vc(t) + Li' = vs(t) Li'' + Ri' + i/C = vs'(t) Where vc is voltage across the capacitor and vs is the source voltage. Q is the charge flowing through the current. 3. The attempt at a solution First I found i(t) through the inductor and the vc prior to the switch opening: 30 = 10i --> i = 3 A 20-vc = 5i --> vc = 5 V Now, I applied the second equation and this is where I become confused. It has to do with the application of Kirchhoff's Voltage Law. i goes through the bottom of the capacitor, so I don't know how to set up the equation. Li'' + Ri' + i/C = 0 i'' + 10i' + 25i = 0 This? i'' + 10i' - 25i = 0 Or this? Likewise, I'll need to find i'(0) after. Would that be: Ri + q(t)/C - q(0)/C + vc(t) + Li' = vs(t) 10 + 5 + i' = 10 This? 10 - 5 + i' = 10 Or this? I think it should be minus in both cases, but the numbers behave weirdly when I try that.