Volume 4, Issue 2, 2011 - hyperion international journal

dable [18]. If for the gravity models, the attractors don’t have a sign(positive, negative), in the Coulomb case the centres of influence have asign and can explain the phenomenon of attraction, or rejection and fromthis perspective we consider it is a close description of actual economicsituations.As it is well known, the electric attractive forces are determined bythe well known Coulomb’s law [17, 18, 19]:q1q2F = K(4)2r12where q1and q2are the interacting electric charges of opposite sign(figure 1).r 12q 2F 12F21q 1Figure 1. The electrical attraction between two electric chargesof different signs.where r12– is the distance between the two charges, and K – is aproportionality constant, that depends on the properties of the environmentbetween the two charges and of the chosen units system. The mostcommon is the International System of Units (S.I.), where K , for12πε+= 1 4πεspherical symmetry and K = , for circular symmetry, ε being thedielectric constant of the environment (electric permittivity).For modelling the phenomenon of migration from neighbour regions(countries) j, with a powerful attraction characterized by a high socioeconomicstatus (material resources, capital, developed logistics, informationsuperstructures, banking, commercial or educational etc.) we willappeal to the notion of field (similar with the electric or electrostatic field)E,which is determined by the ratio of the power/force (electricity) F ofthe attractor and the charge q 0 on which acts the field [18]:FE = (5)q 0278