A dielectric-filled parallel-plate capacitor has plate area of 20.0 and plate separation of 5.00 . The capacitor is connected to a battery that creates a constant voltage of 7.50 . The dielectric constant is 2.00. Throughout the problem, use 8.85×10−12 . The dielectric plate is now slowly pulled out of the capacitor, which remains connected to the battery. Find the energy of the capacitor at the moment when the capacitor is half-filled with the dielectric.Express your answer numerically in joules. I got confused ... and i am lost.. what equation should i use?