电磁学是由电场、电路、磁场、电磁感应和交流电五部分组成。其中电场、电路、磁场等相关知识是进一步认识电磁感应本质的基础,同时,电磁感应知识又是认识交变电流的起点,因此,《电磁感应》是电磁学中承上启下的一章,是电磁学中的重 Electromagnetism is composed of electric field, circuit, magnetic field, electromagnetic induction and alternating current. Among them, electric field, circuit, magnetic field and other related knowledge are the basis for further understanding of the essence of electromagnetic induction. At the same time, the knowledge of electromagnetic induction is the starting point for understanding alternating current. Therefore, “electromagnetic induction” is the chapter of electromagnetics, In the heavy