Question

In the circuit shown in figure the ratio of charge on $5\mu F$ and $2\mu F$ capacitor is :

• A. $5/4$
• B. $5/3$
• C. $3/8$
• D. none of these

Answer 1

Answer: (D)

none of these

As the capacitor 5 and combine (3,2) are in parallel so across 5 and (3,2) will be same.
i.e, $V_5=V_{32}=6V$
Charge on capacitor 5 is $q_5=C_5{V}_5=5\times 6=30\mu C$
The equivalent capacitance for (3,2) is $C_{32}=\frac{3\times 2}{3+2}=6/5\mu F$
equivalent charge $Q_{32}=C_{32}{V}_{32}=\left(6/5\right)\left(6\right)=7.2\mu C$
As the capacitors 3 and 2 are in series so charge on 2 and 3 is equal to $Q_{32}$. i.e,
$q_2=7.2\mu C$.
$\therefore \frac{q_5}{q_2}=\frac{30}{7.2}=10/2.4=5/1.2$