Q.

Regard as two small metal balls one having a charge of +1 micro-coulombs and the other having a charge of +3 micro-coulombs. The balls are get into momentary contact with each other assume each ball is on the end of its own non-conducting rod for handling purposes and then separated. What is the charge on each one ball then?

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For the reason that both charged objects are conductors once they touch the charge is free to go anywhere on the two objects. For the reason that it is all the same kind of charge the charge will distribute itself so that it is on the average as spread out as possible. On basis of symmetry because the two objects are identical half the charge will wind up on one ball and half on the other. Since there were initially four micro-coulombs of charge there must by conservation of charge, be four micro-coulombs of charge in the final arrangement. Dividing this with two there must be 2 micro-coulombs of charge on each metal ball.