Physics · Electrostatic Potential

The electrostatic potential energy \( U \) of a system of two point charges \( q_1 \) and \( q_2 \) separated by a distance \( r_{12} \) in vacuum is expressed as:

1. A
   \( U = \frac{1}{4\pi\varepsilon_0} \frac{q_1 q_2}{r_{12}} \) / \( U = \frac{1}{4\pi\varepsilon_0} \frac{q_1 q_2}{r_{12}} \)
2. B
   \( U = \frac{1}{4\pi\varepsilon_0} \frac{q_1 q_2}{r_{12}^2} \) / \( U = \frac{1}{4\pi\varepsilon_0} \frac{q_1 q_2}{r_{12}^2} \)
3. C
   \( U = \frac{1}{4\pi\varepsilon_0} \frac{(q_1 + q_2)}{r_{12}} \) / \( U = \frac{1}{4\pi\varepsilon_0} \frac{(q_1 + q_2)}{r_{12}} \)
4. D
   \( U = \frac{1}{4\pi\varepsilon_0} \frac{q_1^2 q_2^2}{r_{12}} \) / \( U = \frac{1}{4\pi\varepsilon_0} \frac{q_1^2 q_2^2}{r_{12}} \)