The potentials on the plates of a capacitor are $+20 \,V$ and $-20 \,V$. The charge on the plate is $40 \,C$. The capacitance of the capacitor is (in $\,F$)

Sixty-four drops are joined together to form a bigger drop. If each small drop has a capacitance $C$,a potential $V$,and a charge $q$,then the capacitance of the bigger drop will be

The capacitance of an isolated sphere of radius $r_1$ is increased by $5$ times,when it is enclosed by an earthed concentric sphere of radius $r_2$. The ratio of their radii is

Two spherical conductors $A$ and $B$ of radii $a$ and $b$ $(b > a)$ are placed concentrically in air. The two are connected by a copper wire as shown in the figure. Then the equivalent capacitance of the system is

The graph shows the variation of voltage $V$ across the plates of two capacitors $A$ and $B$ versus the charge $Q$ stored in them. Then:

Capacitance of an isolated conducting sphere of radius $R_{1}$ becomes $n$ times when it is enclosed by a concentric conducting sphere of radius $R_{2}$ connected to earth. The ratio of their radii $\left(\frac{R_{2}}{R_{1}}\right)$ is: