A parallel plate capacitor connected to a battery develops a potential difference across its plates. By integrating the equation relating voltage and current, an equation for the voltage across the capacitor at any given time is determined. Capacitors possess memory, meaning their voltage depends on the past current flow. The instantaneous power delivered to a capacitor is integrated over time to determine the energy stored in the capacitor. An uncharged capacitor has a zero voltage. So, the energy stored in the capacitor is determined in terms of charge and capacitance, which represents the energy present in the electric field between the plates. This energy can be retrieved as an ideal capacitor does not dissipate energy. A non-ideal capacitor has a parallel-model leakage resistance, usually high enough to be neglected in most practical applications. A capacitor can get charged when connected to a battery but acts as an open circuit to DC voltage. The voltage across a capacitor is always continuous and cannot change abruptly.