$90 \ J$ 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 $V$)

$A$ charge $(-q)$ and another charge $(+Q)$ are kept at two points $A$ and $B$ respectively. Keeping the charge $(+Q)$ fixed at $B$,the charge $(-q)$ at $A$ is moved to another point $C$ such that $ABC$ forms an equilateral triangle of side $l$. The net work done in moving the charge $(-q)$ is

Write an equation for the electric potential due to a system of charges.

$A$ particle has a mass $400$ times that of an electron and a charge double that of an electron. It is accelerated by a potential difference of $5 \ V$. If the particle was initially at rest,what will be its final kinetic energy in $eV$?

The electric potential at the surface of a hollow metallic sphere is $10\, V$. What will be the electric potential at its center (in $, V$)?

$A$ non-conducting ring of radius $0.5\,m$ carries a total charge of $1.11 \times 10^{-10}\,C$ distributed non-uniformly on its circumference,producing an electric field $\vec{E}$ everywhere in space. The value of the line integral $\int_{l = \infty }^{l = 0} { - \vec{E} \cdot d\vec{l} }$ (where $l = 0$ is the centre of the ring) in volts is: