Practice question

**Common potential** after connection is weighted average of initial potentials by capacitances. Energy loss ΔU = ½ C₁ C₂ (V₁-V₂)²/(C₁+C₂) dissipated as heat and spark, always positive unless V₁=V₂, explaining why energy reduces after sharing. Initial energy: U_i = (1/2) × 6 × 10⁻⁶ × (150)² = 0.0675 J . Charge: Q = 6 × 10⁻⁶ × 150 = 9 × 10⁻⁴ C . Total C = 6 + 9 = 15 μF , V = (9 × 10⁻⁴/15 × 10⁻⁶) = 60 V . Final energy: U_f = (1/2) × 15 × 10⁻⁶ × (60)² = 0.027 J . Loss: U_i - U_f =