Science Assessment

Two oppositely charged particles are positioned as pictured in Figure 1. A student moves the particles so that the distance between the two particles is decreased as shown in Figure 2. He secures the particles in place so neither can move. The strength of the charges remains the same the whole time.

Which of the following statements correctly describes the change in electrostatic potential energy of the system of two particles from Figure 1 to Figure 2?

1. The electrostatic potential energy increased because the force between any two particles increases as the distance decreases.
2. The electrostatic potential energy decreased because potential energy decreases when the distance between any two particles decreases.
3. The electrostatic potential energy decreased because potential energy decreases when the distance between the oppositely charged particles decreases.
4. The electrostatic potential energy did not changed because the only way to change the potential energy of a system of oppositely charged particles is to change the strength of the charges.