9. A certain capacitor consists of two parallel square metal plates with sides 20 cm and separated in a vaccum. The plates carry an equal and opposite charge of 60nC.

The potential difference across the plates is 1000V. a) What is the capacitance, C, of the capacitor? b) How far apart are they in mm? c) How much energy is stored in the capacitor? d) What is the energy density, U? e) How strong is the electric field E between the plates? f) In which direction does the E field point? g) What is the new capacitance, C, of the capacitor? h) How much energy is now stored in the capacitor? i) What is the energy density, U with the glass dielectric? j) How strong is the electric field E between the plates now?