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. The density of electric field lines represents the magnitude of the field. Closer lines indicate a stronger field because the field strength is proportional to the number of lines per unit area, a convention derived from the inverse-square law and field intensity. Substituting values gives Line density, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.