Three capacitors,each of capacitance $C$ and breakdown voltage $V$,are connected in series. Find the equivalent capacitance and the equivalent breakdown voltage.

Four identical metal plates are arranged in air at equal distances from each other as shown in the figure. Each plate has an area $A$. Find the equivalent capacitance of the system between points $A$ and $B$.

The equivalent capacitance between the points $A$ and $B$ in the given diagram is

$A$ series combination of three capacitors of capacities $1\,\mu F$,$2\,\mu F$,and $8\,\mu F$ is connected to a battery of $e.m.f.$ $13\,V$. The potential difference across the plates of the $2\,\mu F$ capacitor will be.....$V$

The potential difference across the $4 \mu F$ capacitor in series with the parallel combination in the following circuit is: (in $V$)

Three parallel plate capacitors of capacitances $4 \mu F$,$6 \mu F$ and $12 \mu F$ are first connected in series and then in parallel. The ratio of the effective capacitances in the two cases is