Experimental practice and lecture about the working principle of electric motors with electrical measurement and dismantlement －How do electric motors work in practice? －

摘要

Experimental practice and lecture entitled “How do electric motors work in practice?” has been offered for middle school students to ascertain the working principle of electric motors. At the first setout, electric motors mounted in all sort of electric devices in our house or on the streets are counted out to impress students how deeply they have penetrated in our daily life. Adopting the Mabuchi FA-130RA electric motor, which you would typically find in a toy, the electric current and the voltage of a motor have been measured. Subsequently the operation principle, how electricity and magnetism work together to spin the motor, and the electric electromotive force which relates to an electric generator have been explained. At the second period, the Mabuchi motors have been disassembled by the students themselves to confirm the structure of an armor, a commutator and blushes to keep a motor spinning. Moreover, by replacing the original ceramic magnets to stronger neodymium magnets, the important relation between strength of the permanent magnet and the rotation speed has been found out experimentally. As questionnaire surveys carried out after the lecture show that 90% of the students get interested in electric motors, the students might experientially comprehend the working principle of electric motors.