Question

Find the charge on $9\mu \text{F}$ capacitor in the given capacitor network.


[Assume that, the capacitors are in steady state]

• A. $60\mu \text{C}$
• B. $90\mu \text{C}$
• C. $120\mu \text{C}$
• D. $150\mu \text{C}$

Answer 1

The correct option is B $90\mu \text{C}$


Let $V$ be the potential at point $\text{P}$ as shown in the figure.

Applying the law conservation of charges on the given capacitor network we get,

$4(V-30)+3(V-30)+5(V-0)+9(V-0)=0$

$\Rightarrow 21V-120-90=0$

$\Rightarrow V=10\text{volts}$



Therefore, Charge of $9\mu \text{F}$ capacitor is $Q_9=9\mu \times 10=90\mu \text{C}$

Hence, option (b) is the correct answer.