Abstract: According to the microscdpic explanation of Ampere force in the traditional physics textbooks, a consequent question came from whether exists a certain inertial references system in which two relatively static homo -charges will attract each other. In order to find this, the Lorentz force formula in the relativistic approximation is firstly deduced, and then which is applied to the calcuiation of the electromagnetic force between two motion char- ges which are relative to each other stationary. Our results demonstrate that the attraction phenomenon between two relative static homo-charges should not occur in anyone inertial references system. By considering the influence of the equivalent opposite sign charges on the interaction force between two electricity metal conductors, a more com- prehensive microscopic explanation of Ampere force is proposed.

Key words: Ampere force, Lorentz force, homo-charges, electromagnetic force