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
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 56 V
When charged capacitors are joined in parallel, charge flows until both are at the same potential, and the total charge is conserved. So the common potential is the total charge divided by the total capacitance.
\( \displaystyle V = \frac{C_1 V_1 + C_2 V_2}{C_1 + C_2} \)
\( \displaystyle V = \frac{C \times 40 + 4C \times 60}{C + 4C} = \frac{40C + 240C}{5C} \)
\( \displaystyle V = \frac{280C}{5C} = 56\,\mathrm{V} \)