24.64 0- Aparallel-plate capacitor Figure P24.64 is made from two plates 12.0 cm on each side and 4.50 mm apart. Half of the space between these plates contains only air, but the other half is lled with Plexiglas of dielec- tric constant 3.40 (Fig. P24.64). An 18.0 V battery is connected across the plates. (a) What is the capacitance of this combination? (Hint: Can you think of this capacitor as equiva- lent to two capacitors in parallel?) (b) How much energy is stored in the capacitor? (c) If we remove the Plexiglas but change nothing else, how much energy will be stored in the capacitor? + + + + + + Plexiglas Air