该教具通过发光二极管的正向导电通,反向截止来演示断电自感现象,不但可观察断电瞬间线圈中产生的自感电流,而且,可观察自感电流的方向,从而较好地演示断电自感现象。一、电路原理图(图1)二、制作材料直流电压或干电池(2～4V)、单刀开关、普通发光二极管、40W日光灯镇流器。图1 The teaching aid demonstrates the self-inductance phenomenon of power-off through the forward conduction of the light-emitting diode and the reverse cut-off. It can not only observe the self-induction current generated in the momentary coil of the power-off, but also can observe the direction of the self-induction current and thus better. Demonstrate power-off self-inductance phenomenon. First, the circuit schematic (Figure 1) Second, the production of materials DC voltage or dry battery (2 ~ 4V), single-pole switch, ordinary light-emitting diode, 40W fluorescent lamp ballast. figure 1