A) A balloon of radius 30.5 cm is sprayed with a metallic coating so that the surface is conducting. A charge of 6.65×10-8 C is placed on the surface. What is the potential on the balloon's surface?
B) Suppose that the some air is let out of the balloon, so that the radius shrinks to 11.5 cm, what is the new potential on the balloon's surface?
C) What is the change in electrical potential energy during the shrinking process? For your own interest, what does the work needed to change the potential energy?