1. The problem statement, all variables and given/known data Expalin how a positively charged insulating rod can be used to give a metal sphere a positive charge. Cam the same rod be used to simultaneously give one sphere a psotive charge and another sphere a negative charge without the rod having to be recharged ?? 2. Relevant equations None 3. The attempt at a solution So I said charge a ball with contact by using the rod. Then, that ball will be - charged. Use the ball to charge the other ball by contact then we have a + charged ball ? Is it true ? How about the second part, I am not really sure.