Question

In the figure shown the charges on $C_2$ and $C_3$ are respectively :
(A) 20$\mu$ C (B) 12$\mu$C (C) 8$\mu$C (D) 16$\mu$C

• A. A, B are correct
• B. C, B are correct
• C. C, D are correct
• D. A, D are correct

Answer 1

Answer: (B)

C, B are correct

$Q=CV$
$Q=\frac{20}{7}\times 7\mu C.$
$Q=20\mu C$
$\to$ we know two capacitors in series must have same charge on them.
$\therefore chargeflow=20\mu c.$
charge of $4\mu fis20\mu c\therefore Vacross4\mu fisV=\frac{Q}{C}=5V$
when capacitors are in parallel potential difference between them will be same.
$\Rightarrow Q_1=C_{1}Vand{Q}_2=C2V,$(V is 90 minus voltage across $4\mu t$ capacitor).
$\Rightarrow Q_1=2\times 4Q_2=3\times 4$
$\Rightarrow Q_1=8\mu C{Q}_2=12\mu C.$
$\therefore$ charge distribution is as follows