question_answer

What happens to the potential energy when (a) two protons are brought close together (b) one proton and one electron are brought close together?

Answer:

              (a) The potential energy increases when two protons are brought closer because work has to be done against the force of repulsion between them. (b) The potential energy decreases when a proton and an electron are brought closer because work is done by the force of attraction between them (origin of the force being the system itself).