The respective radii of the two spheres of a spherical condenser are $12 \; cm$ and $9 \; cm$. The dielectric constant of the medium between them is $6$. The capacity of the condenser will be

$A$ spherical capacitor is made of two spherical shells of radii $a$ and $b$ $(b > a)$. The medium between the shells is air. What is the difference between the capacitances when the outer shell is grounded and when the inner shell is grounded?

$A$ spherical capacitor has an outer sphere of radius $5 \text{ cm}$ and an inner sphere of radius $2 \text{ cm}$. When the inner sphere is earthed,its capacity is $C_1$,and when the outer sphere is earthed,its capacity is $C_2$. Then $\frac{C_1}{C_2}$ is

Assume each oil drop has a capacitance of $C$. If $n$ drops are combined to form a bigger drop,then the capacitance of the bigger drop $C^{\prime}$ would be

What is the capacitance of a spherical conductor with a radius of $1 \ m$?

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