What is the order of electric potential generated by a Van de Graaff generator?

Write an expression for the potential at a point outside a uniformly charged spherical shell,on the surface,and inside the shell.

Two tiny spheres carrying charges $1.8 \mu C$ and $2.8 \mu C$ are located $40 \ cm$ apart. The potential at the mid-point of the line joining the two charges is:

Write expressions for electric potential due to a continuous distribution of charges.

The total charge on a uniformly charged spherical shell having radius $R$ is $Q$. Then electric potential at a distance $r = R/2$ from the centre of the shell is . . . . . . .

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