Two capacitors of capacitances C and 4C at potentials 40 V and 60 V, respectively are connected in parallel. The common potential of the combination is

56 V

The correct answer is Option (4) → 56 V

When capacitors are connected in parallel, total charge is conserved:

Total charge before connection: $Q_{\text{total}} = Q_1 + Q_2 = C V_1 + 4C V_2$

Given: $V_1 = 40 \ \text{V}$, $V_2 = 60 \ \text{V}$

$Q_{\text{total}} = C \cdot 40 + 4C \cdot 60 = 40C + 240C = 280C$

Total capacitance in parallel: $C_{\text{eq}} = C + 4C = 5C$

Common potential: $V = \frac{Q_{\text{total}}}{C_{\text{eq}}} = \frac{280C}{5C} = 56 \ \text{V}$

Common potential = 56 V