Two 10-cm-diameter electrodes 0.50 cm apart form a parallelplate capacitor. The electrodes are attached by metal wires to the terminals of a 15 V battery. After a long time, the capacitor is disconnected from the battery but is not discharged. What are the charge on each electrode, the electric field strength inside the capacitor, and the potential difference between the electrodes 

a. Right after the battery is disconnected? 

b. After insulating handles are used to pull the electrodes away from each other until they are 1.0 cm apart? 

c. After the original electrodes (not the modified electrodes of part b) are expanded until they are 20 cm in diameter?