A negative charge sits 10 m from a fixed positive charge. In which direction should the negative charge be moved to increase the potential energy of this two-charge system?

1. For charges of opposite sign, the potential energy U_E = kq1q2/r is negative, and it becomes more negative, meaning smaller, as r gets larger. 2. Increasing the potential energy of an opposite-sign pair therefore means making it less negative, which happens as the charges get closer together. 3. Moving the negative charge closer to the fixed positive charge raises the potential energy. 4. Moving it farther away, as in option B, would lower the potential energy further instead of raising it, which is the sign trap for attractive pairs. _Source: OpenStax Physics (CC BY 4.0), Ch 18 "Static Electricity", section 18.4 Electric Potential_