State gauss theorem.using the theorem obtain an expression for force acting between two point charges placed a certain distance apart in vacuum

Gauss's law states that net electric flux through a closed surface is equal to the net charge enclosed by the surface divided by the permittivity of free space, i.e. Integral ( E.ds)=q/(epsilon naught) Where E is the net electric field. Now, consider any one of this etwo point charges and take a spherical gaussian surface of radius equal to the distance between those two point charges and apply the gauss law over that surface to obtain electric field at the location of the other point charge. Suppose the charge due to which we will find electric field is q and the two chargses are separated by distance 'r' then by gauss law we have E(4πr²)=q/(epsilon naught) Hence, E = kq/r² where k=1/4π(epsilon naught) And we know that force on any charges particle is given by F=(charge)(electric field) Therefore, required force is, if other point charge is Q then F=QE and direction depends whether the charges are of same nature or opposite.