Answer: -1.8 × 105 V.
- A -2.7 × 105 V
- B -9.0 × 104 V
- C -1.8 × 105 V
- D +1.8 × 105 V
Correct answer: C. -1.8 × 105 V
Explanation: Each charge is 0.2 m from the midpoint. V = k(q1 + q2)/r = 9 × 109 × (-4 × 10-6)/0.2 = -1.8 × 105 V.
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.