Eight drops of mercury of equal radii combine to form a big drop. The capacitance of the bigger drop as compared to each smaller drop is:

A slab of copper of thickness $b$ is inserted in between the plates of parallel plate capacitor as shown in figure. The separation of the plate is $d.$ If $b=\frac{d}{2},$ then the ratio of capacities of the capacitor after and before inserting the slab will be

Consider a parallel plate capacitor of capacity $10 \mu \mathrm{F}$ with air-filled in the gap between the plates. Now, one-half of the space between the plates is filled with a dielectric of dielectric constant $4,$ as shown in the figure. The capacity of the capacitor changes to,

Four capacitors are connected in a circuit as shown in the figure. The effective capacitance between points $A$ and $B$ will be

The equivalent capacitance between the points $A$ and $C$ is given by