Question

For two like charges (q1q2 > 0), the sign of the mutual Coulombic interaction energy \[\frac{q_1q_2}{4\pi\varepsilon_0 r_{12}}\] is __________, indicating a __________ force.

Options

• negative; repulsive

• negative; attractive

• positive; repulsive

• positive; attractive

Answer 1

When q1 and q2 are like charges, their product q1q2 is positive. Therefore, the Coulomb interaction energy is positive, which physically means that work must be done to bring the charges together against the repulsive force between them.