In a spherical condenser radius of the outer sphere is $R$. The different in the radii of outer and inner sphere in $x$. Its capacity is proportional to
$\frac{{xR}}{{(R - x)}}$
$\frac{{x(R - x)}}{r}$
$\frac{{R(R - x)}}{x}$
$\frac{R}{x}$
A cylindrical capacitor has two co-axial cylinders of length $20 \,cm$ and radii $2 r$ and $r$. Inner cylinder is given a charge $10 \,\mu C$ and outer cylinder a charge of $-10 \,\mu C$. The potential difference between the two cylinders will be
The potentials of the two plates of capacitor are $+10\,V$ and $-10\, V$. The charge on one of the plates is $40 \,C$. The capacitance of the capacitor is........$F$
$1000$ small water drops each of capacitance $C$ join together to form one large spherical drop. The capacitance of bigger sphere is ......... $C$
Eight drops of mercury of equal radii possessing equal charges combine to form a big drop. Then the capacitance of bigger drop compared to each individual small drop is........$times$
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: