Four plates of the same area of cross-section are joined as shown in the figure. The distance between each plate is $d$. The equivalent capacitance across $A$ and $B$ will be

Five capacitors,each of value $1 \mu F$,are connected as shown in the figure. The equivalent capacitance between $A$ and $B$ is (in $\mu F$)

Seven capacitors,each of capacitance $2 \mu F$,are connected in a configuration to obtain an effective capacitance of $\frac{6}{13} \mu F$. The combination that will achieve this is:

Two parallel plate capacitors are connected in series. Each capacitor has a plate area $A$ and a separation $d$ between the plates. The dielectric constants of the media between their plates are $2$ and $4$. The separation between the plates of a single air capacitor of plate area $A$ which effectively replaces the combination is:

Find the equivalent capacitance between the points $A$ and $B$ in the given figure.

Two equal capacitors are first connected in series and then in parallel. The ratio of the equivalent capacities in the two cases will be