Answer: kQ/a2.
- A Zero
- B kQ/a2
- C 5kQ/a2
- D kQ/(5a2)
Correct answer: B. kQ/a2
Explanation: 6 equal charges would give zero field at center. 5 charges = 6 - 1. Field = field of the missing 6th charge = kQ/a2 pointing toward the empty corner.
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.