Practice question

**Flux definition** Φ = ∮ E·dA links field to area orientation. For uniform E perpendicular to surface, Φ = E A, with A = πr² for circle. Inclination reduces flux by cosθ factor, sign indicating outward or inward crossing. Total flux: Φ = (q/ε₀) = (13 × 10⁻⁶/8.854 × 10⁻¹²) = 1.468 × 10⁶ N·m²/C . Flux per face (6 faces): Φfₐcₑ = (1.468 × 10⁶/6) = 2.447 × 10⁵ N·m²/C . Substituting values gives 2.45 × 10⁵ N·m²/C, which matches expected magnitude for this electrostatic configuration, confirming Coulomb's and Gauss's principles and charge quantization consistency.