The capacity of a parallel plate condenser is $15\,\mu \,F$, when the distance between its plates is $6 \,cm$. If the distance between the plates is reduced to $2\, cm$, then the capacity of this parallel plate condenser will be......$\mu \,F$

A $30\,\mu F$ capacitor is charged by a constant current of $30\, mA$. If the capacitor is initially uncharged, how long does it take for the potential difference to reach $400\, V$.....$s$

This question has Statement $1$ and Statement $2$. Of the four choices given after the Statements, choose the one that best describes the two Statements.

Statement $1$ : It is not possible to make a sphere of capacity $1$ farad using a conducting material.
Statement $2$ : It is possible for earth as its radius is $6.4\times10^6\, m$

We have three identical metallic spheres $A, B$ and $C$. $A$ is given a charge $Q$, and $B$ and $C$ are uncharged. The following processes of touching of two spheres are carried out in succession. Each process is carried out with sufficient time.
$(i)$ $A$ and $B$      $(ii)$ $B$ and $C$
$(iii)$ $C$ and $A$      $(iv)$ $A$ and $B$
$(v)$ $B$ and $C$
The final charges on the spheres are

$64$ drops each having the capacity $C$ and potential $V$ are combined to form a big drop. If the charge on the small drop is $q$, then the charge on the big drop will be

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: