Practice question

**Vector addition of forces** underlies multi-charge analysis. Each pair contributes independent Coulomb force, resultant obtained by resolving components along axes. Equilibrium occurs when vector sum vanishes, often at symmetric points where contributions balance. In equilibrium, the field inside a conductor is zero. Any tangential component outside would drive surface charge motion, violating equilibrium. Thus, the field must be perpendicular to avoid such motion, maintaining static conditions. Substituting values gives Equilibrium condition, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.