Answer: -0.18 J.
- A +0.18 J
- B -0.09 J
- C -0.18 J
- D +0.36 J
Correct answer: C. -0.18 J
Explanation: Potential energy is U = kq1q2/r = 9 × 109 × 2 × 10-6 × -3 × 10-6/0.3 = -0.18 J.
Field lines always point from positive to negative charge, are denser where the field is stronger, and never cross; an isolated positive charge has lines radiating symmetrically outward, while a dipole's lines curve from the positive to the negative charge.
Concept context
Coulomb's law, electric field, potential, capacitors, Gauss's law.