Practice question

**Coulomb's law** gives force between point charges as F = k·|q₁q₂|/r², k = 1/(4π ε₀) = 9×10⁹ N·m²/C², directed along line joining charges. Like charges repel, opposite attract, magnitude scales with product of charges and inverse square of separation r². Negative charge means electrons are gained. q = n e , e = -1.6 × 10⁻¹⁹ C . n = (q/|e|) = (4.8 × 10⁻⁸/1.6 × 10⁻¹⁹) = 3 × 10¹¹ . Substituting values gives 3 × 10¹¹, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.