The
number of field lines, cutting unit area element is therefore n/(
2
1r DW) at
P1 and n/(
2
2r DW) at P2, respectively Since n and DW are common, the
strength of the field clearly has a 1/r 2 dependence The picture of field lines was invented by Faraday to develop an
intuitive non-mathematical way of visualising electric fields around
charged configurations Faraday called them lines of force