Two positive point charges of $10 \ \mu C$ and $12 \ \mu C$ are placed $10 \ cm$ apart in air. The work done to bring them $6 \ cm$ closer is (in $J$)

$A$ molecule of a substance has a permanent dipole moment $p$. $A$ mole of this substance is polarized by applying a strong electrostatic field $E$. The direction of the field is suddenly changed by an angle of $60^{\circ}$. If $N$ is the Avogadro's number,the amount of work done by the field is:

$A$ proton is moving away from an electron. Find the change in the potential energy of the system.

In bringing an electron towards another electron,the electrostatic potential energy of the system

When one electron is moved towards another electron,the electric potential energy of the system:

Obtain the equation of electric potential energy of a dipole from the equation of potential energy of a system of two electric charges.