21. A metal ball with a radius of R = 10 cm carries a charge of Q = 5 nC. Determine the potential φ of the electrostatic field: 1) in the center of the ball; 2) on the surface of the ball; 3) at a distance l = 5 cm from its surface. Build a plot of φ (r).

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