Question

The capacitor, whose capacitance is 6, 6 and $3\mu F$ respectively are connected in series with 20 volt line. Find the charge on $3\mu F$.

• A. $30\mu C$
• B. $60\mu F$
• C. $15\mu F$
• D. $90\mu F$

Answer 1

The correct option is A $30\mu C$

If $C_{eq}$ is the equivalent capacitance , $\frac{1}{C}=\frac{1}{C}+\frac{1}{C}+\frac{1}{C}=1/6+1/6+1/3=2/3$
or $C=3/2\mu F$
Equivalent charge $Q_{eq}=C_{eq}V=\left(3/2\right)20=30\mu F$
As all capacitors are in series so charge on each capacitor is equal to $Q_{eq}$.
The charge on $3\mu F=30\mu C$