(2 18)
If we have a continuous charge distribution characterised by a charge
density r (r), we divide it, as before, into small volume elements each of
size Dv and carrying a charge rDv We then determine the potential due
to each volume element and sum (strictly speaking , integrate) over all
such contributions, and thus determine the potential due to the entire
distribution We have seen in Chapter 1 that for a uniformly charged spherical shell,
the electric field outside the shell is as if the entire charge is concentrated
at the centre