Potential energy of point-charges: Suppose you have two point charges of opposite sign. As you move them farther and farther apart, the potential energy of this system relative to infinity

Question

Quizplus · Accepted Answer

The potential energy of the system of two opposite point charges increases as they are moved farther apart, because the work needed to move them from a distance r1 to a distance r2 (where r2>r1) against the electrostatic force of attraction is given by the expression U = kq1q2(1/r2 - 1/r1), where q1 and q2 are the charges, r1 and r2 are the initial and final distances, and k is the Coulomb constant. Since 1/r2 < 1/r1, the difference (1/r2 - 1/r1) is positive, so work is done on the system and its potential energy increases.

Potential Energy of Point-Charges: Suppose You Have Two Point Charges