Question

when two protons are brought nearer then potential energy increase why?

Answer 1

as the are both positive charge so they repel each other so they act like two end of coil spring

Answer 2

We know, Proton consist of positive charged particles. So, when they brought near they may repel. They may statute like coiled spring. They are picked in the form of P.E. 

P.E decreases when we brought proton and electron near as the work done by intermoleculer force. So, when we brought two proton near then P.E will increase.