The potential at a point,due to a positive charge of $100\,\mu C$ at a distance of $9\,m$,is

Three identical charges of $10 \ \mu C$ are placed at the vertices of an equilateral triangle of side $10 \ cm$. The electrostatic potential energy of the system is ....... $J$.

$A$ particle of charge $Q$ and mass $m$ travels through a potential difference $V$ from rest. The final momentum of the particle is

Two point charges $q_1 = 4 \times 10^{-8} \ C$ and $q_2 = -6 \times 10^{-8} \ C$ are placed at points $A$ and $B$ respectively,which are $50 \ cm$ apart. At what distance from point $A$ on the line $AB$ is the electric potential zero (in $cm$)?

Along the $X$-axis,three charges $\frac{q}{2}, -q$ and $\frac{q}{2}$ are placed at $x=0, x=a$ and $x=2a$ respectively. The resultant electric potential at $x=a+r$ (if $a << r$) is: ($\varepsilon_0$ is the permittivity of free space)

The figure shows a charge array known as an electric quadrupole. For a point on the axis of the quadrupole,obtain the dependence of potential on $r$ for $r / a >> 1,$ and contrast your results with that due to an electric dipole,and an electric monopole (i.e.,a single charge).