Two particles with charges +7e and -6e are initially very far apart (effectively an infinite distance apart). they are then fixed at positions that are 7.50 x 10^-12 m apart. what is epefinal - epeinitial, which is the change in the electric potential energy?

Explanation:

The formula for electric potential energy between 2 charges and separated a distance r is , where is the Coulomb constant.

The initial electric potential energy is then 0J, since r is infinite.

The final electric potential energy is

Where is the elementary charge.

Substituting values we have:

So we finally have:

what is the actual question though?