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

Consider a fixed uniformly charged insulating sphere with radius $R$ and total charge $+Q$. $A$ point charge $-q$ $(q \ll Q)$ with mass $m$ is released from rest at a distance of $3R$ from the centre of the charged sphere. When the point charge reaches the surface of the sphere, its speed is:
($\epsilon_0$ is the permittivity of vacuum, neglect gravitational forces).

$A$ charge of $20 \, C$ moves through a distance of $2 \, cm$. The work done is $2 \, J$. The potential difference between the two points is ........ $V$.

$A$ neutral spherical copper particle has a radius of $10 \,nm$ $(1 \,nm = 10^{-9} \,m)$. It gets charged by applying the voltage,slowly adding one electron at a time. Then,the graph of the total charge on the particle versus the applied voltage would look like:

Derive the formula for the electric potential energy of a system of three charges.

Define $1 \ eV$.