Final answer:
The potential energy of charge q1 in the presence of charge q2 is given by U = kq1q2/r, representing the work done to bring q2 from infinity to a distance r from q1.
Step-by-step explanation:
The potential energy of charge q1 in the presence of another charge q2 is a measure of the work done to bring q2 from infinity to a distance r from q1. The formula for the electric potential energy of a pair of point charges is given by U = kq1q2/r, where k is the Coulomb's constant, q1 and q2 are the magnitudes of the charges, and r is the distance between the charges. This expression reflects the energy required per unit charge to assemble the two charges at a distance r apart, considering that the two charges have the same sign and are repulsive.