Practice question

**Sharing of charges** when charged capacitor C₁ at V₁ connected to uncharged C₂, total charge Q = C₁ V₁ conserved, common potential V_common = Q/(C₁+C₂) = C₁ V₁/(C₁+C₂), final charges Q₁' = C₁ V_common, Q₂' = C₂ V_common. For 4 μF at 100 V (Q=4×10⁻⁴ C) connected to 4 μF uncharged, V_common=4×10⁻⁴/8×10⁻⁶=50 V. Initial charge: Q = 10 × 10⁻⁶ × 40 = 4 × 10⁻⁴ C . Total capacitance: 10 + 10 = 20 μF . Final voltage: V = (Q/C) = (4 × 10⁻⁴/20 × 10⁻⁶) = 20 V . Using V = kQ/r, U = k q₁q₂/r, E = -dV/dr, C =