What will happen if we attach a charged capacitor to an inductor? Of course, the capacitor will discharge, causing a current to flow in the inductor. If the voltage across the capacitor has become zero, there will still be a current flow in the inductor. This current will re-charge the capacitor. The voltage across it will become negative. When the indictor has transferred all its energy to the capacitor, the capacitor will discharge again. Next, the inductor will charge the capacitor and everything will start all over again. This is called oscillation. The frequency equals: