Question

why is it tat in a conductor charges re-distribute only on the outer surface,or does it mean tat maximum charges r on the outside and charges r minimum inside?

Answer 1

In a conductor an excess or deficit of electrons will certainly be equally distributed over its volume (considering that it has a constant density and constitution), but the effect of that charge will only be measurable by contrasting it to an opposite charge, in doing so the field created by the conductor emanates from its surface. There is also the consideration that to answer to an equation containing an integral over the volume with a constant or not density is a rather laborious task evaded by stating the points You are intrigued with.

Answer 2

why only the surface ? how did they come to know its from surface ? by what experiment ?? elobrate please sir !