capacitance
When a capacitor is placed in a circuit, current does not actually travel across it. Rather, equal and opposite charge begins to build up on opposite sides of the capacitor --- mimicking a current --- until the electric field in the capacitor creates a potential difference across it that balances the voltage drop across any parallel resistors or the voltage source itself if there are no resistors in parallel with the capacitor . The ratio of charge on a capacitor to potential difference across it is called capacitance.