For a conducting sphere of radius $R$ carrying a charge $Q$,what is the electric potential at a distance $x$ from the center inside the sphere?

Two point charges are located on the $x$-axis. $q_1 = -1 \ \mu C$ at $x = 0$ and $q_2 = +1 \ \mu C$ at $x = 1 \ m$. Find the work done in bringing a third charge $q_3 = +1 \ \mu C$ from infinity to $x = 2 \ m$.

Two positive charges $Q$ and $4Q$ are placed at points $A$ and $B$ respectively,where $B$ is at a distance $d$ units to the right of $A$. The total electric potential due to these charges is minimum at point $P$ on the line segment joining $A$ and $B$. What is the distance of $P$ from $A$?

The electric potential at a distance of $R/2$ from the center of a charged conducting sphere of radius $R$ is .......

What is the electric potential at a distance of $9 \text{ cm}$ from a charge of $3 \text{ nC}$ (in $\text{ V}$)?

Define electron volt and convert it into Joule unit.