Question

Three capacitors $A,B$, and $C$ are connected in a circuit as shown in figure. What is the charge in $\mu C$ on the capacitor $B$ ?

• A. $1/3$
• B. $2/3$
• C. $1$
• D. $4/3$

Answer 1

Answer: (B)

Capacitors $B$ and $C$ are in parallel, then $A$ is in series.
$C_{eq}=\frac{2\times (3+4)}{2+(3+4)}=\frac{14}{9}\mu F$
$Q=C_{eq}V=\frac{14}{9}(7-6)=\frac{14}{9}\mu C$
$Q$ will be divided between $B$ and $C$. So charge on $B$ is
$q=\frac{3\times (14/9)}{3+4}=\frac{2}{3}\mu C$