在教材中,自感现象演示实验所用仪器为通、断电自感现象的演示装置、电源、开关及导线若干,实验装置如图1、图2所示。演示通电和断电的自感现象时,分成2个电路,不仅演示时不够方便,而且会使学生误以为每种线圈只能在一种条件下产生自感电动势,造成不必要的歧义,同时感应电流的方向也无法展现出来。 In the teaching materials, self-inductance phenomena are used to demonstrate the equipment used in the experiment, such as demonstration devices, power supplies, switches, and wires. The experimental devices are shown in Figures 1 and 2. Demonstrating the self-induction phenomenon of power-on and power-off is divided into two circuits, which is not only inconvenient for demonstration, but also makes students mistakenly believe that each type of coil can only generate self-induced electromotive force under one condition, causing unnecessary ambiguity. The direction of the induced current cannot be demonstrated.