Answer: zero.
- A zero
- B kq/d²
- C 2kq/(d/2)²
- D 4kq/d²
Correct answer: A. zero
Explanation: The two fields at the midpoint are equal and opposite, so they cancel and the net field is zero.
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.