What Happens as Time Goes By?

Consider an insulating rod that is given a net charge at one end. Which diagram correctly shows the charge distribution after some time has passed? Diagram 1 shows the initial situation.

  1. Diagram 1 - no change from the initial situation
  2. Diagram 2 - some change from the initial situation
  3. Diagram 3 - uniform distribution
  4. Diagram 4 - concentrated at the ends
  5. Diagram 5 - concentrated in the center

In an ideal insulator the charge should stay where it is, so diagram 1 is correct. A real insulator will allow some migration of the charge, but this change will happen slowly.