Question

Consider the circuit given in figure. The charge in $\mu C$ on the capacitor having capacity $5\mu F$ is

• A. 21
• B. 3.6
• C. 9
• D. 12.6

Answer 1

Answer: (C)

$C_2$ and $C_3$ are in parallel
$\therefore C_4=C_2+C_3=7\mu F$
$C_1$ and $C_4$ are in series
$\therefore \frac{1}{C_{cq}}=\frac{1}{7}+\frac{1}{3}=\frac{10}{21}$
or $C_{eq}=2.1\mu F$
Therefore, the total charge
across the arm $Ab=2.1\times 6=12.6\mu C$
The total potential across $C_2$ and $C_3$ is
$V=\frac{12.6}{7}=1.8V$
$\therefore$ Charge across $5\mu F=1.8\times 5=9\mu C$