Practice question

**Line charge concept** extends point charge to infinite wire where symmetry dictates radial field proportional to λ and inversely proportional to distance r. λ = q/L for uniform case, field direction depends on sign of λ, outward for positive. E = (sigma/2 ε₀) . E = (1.77 × 10⁻¹⁰/2 × 8.854 × 10⁻¹²) = 10 N/C . Substituting values gives 10 N/C, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.