The work done to take an electron from rest where potential is $-60\, V$ to another point where potential is $-20\, V$ is given by.....$eV$

A metallic sphere has a charge of $10\,\mu C$. A unit negative charge is brought from $A$ to $B$ both $100\,cm$ away from the sphere but $A$ being east of it while $B$ being on west. The net work done is........$joule$

Two identical thin rings, each of radius $R $ meter are coaxially placed at distance $R$ meter apart. If $Q_1$ and $Q_2$ coulomb are respectively the charges uniformly spread on the two rings, the work done in moving a charge $q$ from the centre of one ring to that of the other is

Derive the formula for the electric potential energy of system of two charges.

Two positrons $(e^+)$ and two protons $(p)$ are kept on four corners of a square of side $a$ as shown in figure. The mass of proton is much larger than the mass of positron. Let $q$ denotes the charge on the proton as well as the positron then the kinetic energies of one of the positrons and one of the protons respectively after a very long time will be-

Explain electrostatic potential energy difference and give the noteworthy comments on it.