Abstract:  Charged particles are assumed to be a standard geometric model, an expression for the migration current, displacement current, and magnetic induction intensity generated by the motion of charged particles is inferred based on the microscopic definition of current intensity, the law of total current, and the Biot Savart law. Further calculate the electric and magnetic field forces between two charged particles running parallel in vacuum, provide the velocity constraint relationship and velocity magnitude criterion for the electric and magnetic field forces, and compare their consistency with the relevant results obtained by considering relativistic effects. It is pointed out that only when the speed of charged particles is close to the speed of light, can magnetic field forces and electric field forces be comparable.

Key words: motion charge, migration current, displacement current, speed of light