Question

A capacitor of capacitance C charged by an amount Q is connected in parallel with an uncharged capacitor of capacitance 2C. The final charges on the capacitors are

• A. $\frac{Q}{3}, \frac{2Q}{3}$
• B. $\frac{Q}{2}, \frac{Q}{2}$
• C. $\frac{Q}{5}, \frac{4Q}{5}$
• D. $\frac{Q}{4}, \frac{3Q}{4}$

Answer 1

Answer: (A)

$\frac{Q}{3}, \frac{2Q}{3}$

Answer 2

The two capacitors attain common potential $\left(V_{c}\right)\quad$ given by the relation.
$V_{c}=\frac{Total \,charge}{Total \,Capacitance}=\frac{Q+0}{C+2C}=\frac{Q}{3C}$
The final charges on two capacitors are
$Q_{1}=CV_{c}=\frac{CQ}{3C}=\frac{Q}{3} \, and \, Q_{2}=2 CV_{c}=\frac{2Q}{3}$