Capacitance, in electricity, is the capability of a body, system, circuit, component or device for storing electric charge. Capacitance is expressed as the ratio of a stored charge in coulombs to the impressed potential difference in volts. The resulting unit of capacitance is designated as the farad. In an electric circuit the component device designed to store such an charge is called a capacitor. An ideal capacitor is one having no resistance and no inductance. The resulting characteristic is capacitance.