Abstract: The computation formulation of motional electromotive force was deduced under special and general conditions,and it was proved that the total lorentz force does not apply work in the course of generating motional electromotive force.Consequently,the reason of generating motional electromotive force is that a component of total lorentz force provides a non-electrostatic force.In the course of generating motional electromotive force,the energy conservation law is satisfied,and lorentz force acts as a implement of energy transfer.

Key words: motional electromotive force, lorentz force, amepere force, non-electrostatic force