No current flows between two charged bodies connected together when they have the same

Capacitance (in $F$) of a spherical conductor with radius $1\, m$ is

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 $400\, V$.....$s$

A spherical capacitor consists of two concentric spherical conductors, held in position by suitable insulating supports (Figure). Show that the capacitance of a spherical capacitor is given by

$C=\frac{4 \pi \varepsilon_{0} r_{1} r_{2}}{r_{1}-r_{2}}$

where $r_{1}$ and $r_{2}$ are the radii of outer and inner spheres, respectively.

A spherical condenser has inner and outer spheres of radii $a$ and $b$ respectively. The space between the two is filled with air. The difference between the capacities of two condensers formed when outer sphere is earthed and when inner sphere is earthed will be

$64$ 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