1. The problem statement, all variables and given/known data 2. Relevant equations V=IZ 3. The attempt at a solution So my plan is as follows: Find the current through the 1 ohm resistor, multiplying this by the combined impedance of the capacitor & 1 ohm resistor. Now I know the voltage across the unkown impedance Z. Subtract this voltage from the 12 V source, now I know the voltage through the 9 ohm resistor. Use KCL to find the current through Z, and use V=IZ to find the unknown impedance. Current through 1 ohm resistor: 4(45d) Voltage through 1 ohm resistor & capacitor: 4(45d)(1-j1)=5.66(0d) Voltage through 9 ohm resistor: 12(0d)-5.66(0d) = 6.34(0d) Current through 9 ohm resistor: 6.34(0d)/9 = 0.7044(0d) By KCL: -Ic + Iz + Io = 0 Iz = Ic - Io = 0.7044(0d) - 4(45d) = 3.54(53d) V/Iz = 5.66(0d)/3.54(53d) = 1.6(-53d) = 0.963-1.278j But this is wrong, and I've been trying to figure this out for a good hour now, but keep getting the same answer. So I conclude that there's something wrong with my approach.