Practice question

**Electric field concept** visualizes influence of source charge. Uniform field exerts constant force F = qE, and flux Φ = E·A = E A cosθ links field to area orientation, maximum when field normal to surface. E = (k |q|/r²) . k = 9 × 10⁹ N·m²/C² , q = 3 × 10⁻⁶ C , r = 3 m . E = 9 × 10⁹ × (3 × 10⁻⁶/(3)²) = 9 × 10⁹ × (3 × 10⁻⁶/9) = 3 × 10³ N/C . Substituting values gives 3 × 10³ N/C, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.