The area density page defines it in a way that contradicts the dictionary definition ( dicdef : of or relating to area ) since the area density article defines it as the reciprocal of area per unit mass, instead of X per unit area where X could also be " unit field lines " ( a term I made up to aid my notes, let a hollow vandegraff sphere of fixed amount of charge be imaginarily divided into N tiles ) which then readily lends to seeing more equations once a tile is defined to have 1 field line of magnitude 1 potential difference per meter.
