$1 \ eV = ...... \ J$. (Fill in the gap)

Two rings of radius $R$ are placed coaxially at a distance $R$ apart. They carry charges $Q_1$ and $Q_2$ respectively. How much work is required to move a charge $q$ from the center of one ring to the center of the other?

$A$ proton is $1840$ times heavier than an electron. When it is accelerated through a potential difference of $1 \ kV$,its kinetic energy is .......... $keV$.

Write expressions for electric potential due to a continuous distribution of charges.

$90 \ J$ of work is done to move an electric charge of magnitude $3 \ C$ from a place $A$,where potential is $-10 \ V$,to another place $B$,where potential is $V_1 \ V$. The value of $V_1$ is: (in $V$)

$A$ unit positive point charge is taken slowly through an infinitesimally thin tube that is inside a charged dielectric sphere of radius $R$, having uniform positive charge density $\rho$. The initial and final positions of the charge are marked by $A$ and $B$ at distances $2R$ and $3R$ respectively, from the centre of the sphere. In this process, the magnitude of the total work done on the point charge is $\frac{\rho R^2}{n \epsilon_0}$. The value of $n$ is : ($\epsilon_0$ is the permittivity of vacuum)