Two hollow conducting spheres of radii $R_{1}$ and $R_{2}$ $(R_{1} >> R_{2})$ have equal charges. The potential would be:

Which one of the following is not a measurable quantity?

Four equal charges $Q$ are placed at the four corners of a square of side $a$. The work done in moving a charge $-Q$ from its centre to infinity is

The charge given to a hollow sphere of radius $10\, cm$ is $3.2 \times 10^{-19}\, C$. At a distance of $4\, cm$ from its centre,the electric potential will be

The potential difference between the center and the surface of a sphere of radius $R$ with a uniform volume charge density $\rho$ within it will be:

Eight charges,each of magnitude $q$,are placed at the vertices of a cube placed in a vacuum. The electric potential at the centre of the cube due to this system of charges is . . . . . . . ($\varepsilon_0 = $ permittivity of vacuum,$a = $ length of each side of the cube.)