Question

A network of four capacitors $5\mu F$ each is connected to a $240V$ supply. Determine charge on $C_4$.

Answer 1

$C_1,C_2$ and $C_3$ are in series

so $\frac{1}{C^{\prime }}=\frac{1}{C_1}+\frac{1}{C_2}+\frac{1}{C_3}=\frac{1}{5}+\frac{1}{5}+\frac{1}{5}$

$C^{\prime }=\frac{5}{3}\mu F$

$C^{\prime }$ and $C_4$ are in parallel

$C_{eq}=C^{\prime }+C_4=\frac{5}{3}+5=\frac{20}{3}\mu F$

Charge on $C_1,C_2$ and $C_3$ will be same

$=C^{\prime }\times V=\frac{5}{3}\times 240=\frac{1200}{3}\mu mC$

Charge on $C_4=C_4{V}_2=C_{4}V=5\times 240=1200\mu C$