Two isolated,concentric,conducting spherical shells have radii $R$ and $2R$ and uniform charges $q$ and $2q$ respectively. If $V_1$ and $V_2$ are potentials at points located at distances $3R$ and $\frac{R}{2}$,respectively,from the centre of the shells,then the ratio $\left(\frac{V_2}{V_1}\right)$ will be:

The energy which an $e^-$ acquires when accelerated through a potential difference of $1 \, V$ is called:

$A$ charge of total amount $Q$ is distributed over two concentric hollow spheres of radii $r$ and $R$ $(R > r)$ such that the surface charge densities on the two spheres are equal. The electric potential at the common centre is

$729$ small identical spheres each charged to an electric potential $3 \ V$ combine to form a bigger sphere. The electric potential of the bigger sphere is (in $V$)

What is the electric potential at a distance of $9 \text{ cm}$ from a charge of $3 \text{ nC}$ (in $\text{ V}$)?

Two small equal point charges of magnitude $q$ are suspended from a common point on the ceiling by insulating massless strings of equal lengths. They come to equilibrium with each string making an angle $\theta$ from the vertical. If the mass of each charge is $m$,then the electrostatic potential at the centre of the line joining them will be $\left( \frac{1}{4\pi \epsilon_0} = k \right).$