Target Exam

CUET

Subject

Physics

Chapter

Electrostatic Potential and Capacitance

Question:

Two capacitors of capacitances 3 μF and 6 μF are charged to potentials of 2 V and 3 V, respectively. Now, if they are connected in parallel, the charge on each of the two capacitors, will be

Options:

6 μC and 18 μC

9 μC and 12 μC

8 μC and 16 μC

24 μC and 24 μC

Correct Answer:

8 μC and 16 μC

Explanation:

The correct answer is Option (3) → 8 μC and 16 μC

Given:

$C_1 = 3\,\mu F,\; V_1 = 2\,V$

$C_2 = 6\,\mu F,\; V_2 = 3\,V$

Initial charges:

$Q_1 = C_1 V_1 = 3 \times 2 = 6\,\mu C$

$Q_2 = C_2 V_2 = 6 \times 3 = 18\,\mu C$

Total charge when connected in parallel:

$Q_{total} = Q_1 + Q_2 = 6 + 18 = 24\,\mu C$

Equivalent capacitance:

$C_{eq} = C_1 + C_2 = 3 + 6 = 9\,\mu F$

Final common potential:

$V_f = \frac{Q_{total}}{C_{eq}} = \frac{24}{9} = \frac{8}{3}\,V \approx 2.67\,V$

Final charge on each capacitor:

$Q_1' = C_1 V_f = 3 \times \frac{8}{3} = 8\,\mu C$

$Q_2' = C_2 V_f = 6 \times \frac{8}{3} = 16\,\mu C$

Final Answer:

$Q_1' = 8\,\mu C,\; Q_2' = 16\,\mu C$