A parallel plate capacitor of capacitance C0 has plates of area A with separation d between them. When it is connected to a battery of voltage V0, it has charge of magnitude Q0 on its plates. It is then disconnected from the battery and the plates are pulled apart to a separation 2d without discharging them. After the plates are 2d apart, the magnitude of the charge on the plates and the potential difference between them are
◦ Q0,
V0
◦ Q0,
V0
◦ Q0, V0
◦ Q0, 2V0
◦ 2Q0, 2V0