Two capacitors of $3 \mu F$ and $6 \mu F$ are connected in series and a potential difference of $900 \ V$ is applied across the combination. They are then disconnected and reconnected in parallel. The potential difference across the combination is

$A$ part of a circuit is shown in the figure. If $V_A - V_B = 4 \, V$,then find the charge on the $4 \, \mu F$ capacitor connected to point $A$. (in $, \mu C$)

$A$ capacitor of $2\,\mu F$ capacitance is charged steadily from $0$ to $5\,C$. Which of the following graphs correctly represents the variation of potential difference $(V)$ across its plates with respect to the charge $(Q)$ on the capacitor?

Find the maximum charge on the capacitor $C$ in the following circuit in $\mu C$.

$A$ parallel plate capacitor has capacitance $C$. If the charges on the plates are $Q$ and $-3Q$,find the potential difference between the plates.

$A$ capacitor of capacitance $C = 900 \, pF$ is charged fully by a $100 \, V$ battery as shown in figure $(a)$. Then it is disconnected from the battery and connected to another uncharged capacitor of capacitance $C = 900 \, pF$ as shown in figure $(b)$. The electrostatic energy stored by the system in figure $(b)$ is $\dots \times 10^{-6} \, J$.