เมื่อ สลับกัน ปัจจุบัน passes through a wire, an alternating magnetic field is generated around the wire. The inside of the whole conductor in the alternating magnetic field will generate an induced ปัจจุบัน. Since this induced current forms a closed loop inside the whole conductor, much like a water vortex, it is called an ไหลวน current. Eddy current will not only waste electric energy in vain, reduce the efficiency of using electrical equipment, but also cause heating of electrical appliances (such as transformer iron core), which will affect the normal operation of equipment in severe cases.