Problems on demonstration of the magnetic field producing the electric field

Based on the present scientific conclusion, this paper summarises electromagnetic induction to obtain three viewpoints, that is: 1. the essence of electromagnetic induction is the movement of metal electrons forced by Lorentz´s force; 2. time-varying magnetic field does not produce an electric field in free space; 3. the observer does not see an electric field while there is relative motion between the observer and the magnetic field