Question

Three capacitors of same capacitance are connected in parallel When they are connected to a cell of $2$ volt, total charge of $1.8\mu C$ is accumulated on them. Now after discharging they are connected m series and then charged by the same cell The total charge stored in them will be:

• A. $1.8\mu C$
• B. $0.9\mu C$
• C. $0.6\mu C$
• D. $0.2\mu C$

Answer 1

The correct option is D $0.2\mu C$

Let capacitance of each capacitor be $C$

Equivalent capacitance of three capacitor connect in parallel

$C_1=C+C+C$

$C_1=3C$

They are connected to a $2V$ battery

So charge stored

$q=3CV$

$1.8\mu C=3CV$

$CV=0.6\mu C$

After discharging the capacitor are connected in series

Now equivalent capacitance

$\frac{1}{C_{eq}}=\frac{1}{C}+\frac{1}{C}+\frac{1}{C}$

$C_{eq}=\frac{C}{3}$

Now charge stored

$q=\frac{CV}{3}$

$q=0.2\mu C$