Let $W$ joule be the work done to move an electric charge $q$ coulomb from a place $A$,where potential is $-5 \ V$,to another place $B$,where potential is $V$ volt. The value of $V$ is

$A$ charge $Q$ is uniformly distributed over a long rod $AB$ of length $L$ as shown in the figure. The electric potential at the point $O$ lying at a distance $L$ from the end $A$ is

Two identical thin rings each of radius $R \text{ m}$ are kept on the same axis at a distance of $R \text{ m}$ apart. If the charges on them are $10 \text{ C}$ and $5 \text{ C}$ respectively,calculate the work done in moving a charge '$q$' coulomb from the centre of one ring to that of another.

The electric potential inside a conducting sphere:

Write an equation for the potential at a point in a uniformly charged spherical shell.

The work done to assemble the three charges in a configuration as shown in the figure is