An experimental parallel-plate capacitor with a solid dielectric slab (εr=4.0\varepsilon_r = 4.0εr=4.0) filling the space between its plates is connected to a high-voltage power supply. The electrical energy stored in this configuration is EEE.
The capacitor is then disconnected from the power supply, isolating the charge on its plates. Following this, the dielectric slab is completely withdrawn, leaving only a vacuum between the plates.
What is the energy now stored in the capacitor?
0.25E0.25E0.25E
EEE
2.0E2.0E2.0E
4.0E4.0E4.0E
