Question

You have two neutral metal spheres on wood stands. Devise a procedure for charging the spheres so that they will have like charges of exactly equal magnitude.

Answer 1

At first, the two metal spheres have the same number of electrons and protons.

Naturally, the negative charges (electrons) will move away from negative and towards positive, you know. But there is a sea of electrons, and the electrons will disperse among themselves until they're staying as far away far away from more electrons.

The electrons in the spheres would naturally move to even out the charge. But the electrons have no path to easily flow along. I mean, a high voltage will "break down" the air and electrons will jump across. But then the potential difference wouldn't be high enough to jump, but still be difference.

So you give them a path - a conductor to let the electrons flow. Pretty much. connect them by a metal rod, or something