31. Two concentric metal spheres with radii r1 = 1 cm and r2 = 1.5 cm form a spherical capacitor. The space between the capacitor plates is filled with oil (ε = 2.2). Determine: 1) the capacitance of this capacitor; 2) what radius ball placed in this oil will have such a capacity?

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)