An air-filled parallel-plate capacitor is charged by connecting it to a DC power supply. The capacitor is then isolated from the power supply. While isolated, the distance between the two plates is doubled.
Which of the following correctly describes the changes to the potential difference across the plates and the electrostatic energy stored in the capacitor?
Potential difference: doubles; Stored energy: doubles
Potential difference: stays the same; Stored energy: halves
Potential difference: halves; Stored energy: halves
Potential difference: doubles; Stored energy: halves