Practice question

**Continuous distribution** uses linear density λ = dq/dl (C/m), surface σ = dq/dA, volume ρ = dq/dV. Field of infinite line with uniform λ is E = 2kλ/r = λ/(2π ε₀ r) radially outward, derived via cylindrical Gaussian surface, showing 1/r dependence. E = (2 k λ/r) . 5.4 × 10⁵ = (2 × 9 × 10⁹ × λ/0.06) . λ = (5.4 × 10⁵ × 0.06/18 × 10⁹) = 1.8 × 10⁻⁶ C/m . Substituting values gives 1.8 × 10⁻⁶ C/m, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.