21)
on the surface of the conductor (which is very small on the macroscopic
scale but big enough to include a very large number of electrons) and
specify the charge DQ on that element We then define a surface charge
density s at the area element by
SQ
σ
= ∆∆
(1 23)
We can do this at different points on the conductor and thus arrive at
a continuous function s, called the surface charge density The surface
charge density s  so defined ignores the quantisation of charge and the
discontinuity in charge distribution at the microscopic level*