So, let's assume the switch has been closed for a long time. The capacitor is charged to 12V, and the coil acts like a short-circuit. Immediately after opening the switch, is it right to say the Voltage in the coil is 12V? My notes specify something along the lines of: the conditions at time 0+ must be the same as the conditions at time 0- to preserve continuity, because instantaneous variations are impossible. Are my notes wrong? Is the voltage in the coil at 0+ really 12V?