The total capacity of the system of capacitors shown in the adjoining figure between the points $A$ and $B$ is.....$\mu F$

Two capacitors $A$ and $B$ are connected in series as shown in the figure. When the switch $S$ is closed and both capacitors are fully charged,then:

Three long concentric conducting cylindrical shells have radii $R$,$2R$,and $2\sqrt{2}R$. The inner and outer shells are connected to each other. The capacitance across the middle and inner shells per unit length is:

Three capacitors $2\,\mu F$,$3\,\mu F$,and $6\,\mu F$ are joined in series with each other. What is the minimum effective capacitance in $\mu F$?

Four capacitors,each of capacitance $16 \mu F$,are connected as shown in the figure. The equivalent capacitance between points $A$ and $B$ is: . . . . . . (in $\mu F$).

Four metallic plates, each with a surface area of one side $A$, are placed at a distance $d$ from each other. The plates are connected as shown in the figure. The capacitance of the system between $a$ and $b$ is