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学过初中物理“生活用电”之后,部分学生对家用电器的金属外壳要接地的原因仍不大清楚。究其原因主要是学生们对触电事故的原因不能透彻理解。在教学实践中,笔者觉得采用图解法来简化和释疑有关问题,效果确实不错。1.若金属外壳不接地。家用电器内部火线的绝缘皮破损或失去绝缘性能,致使火线与外壳接通,外壳带了电,那么站在地上的人(假设与地
After learning how to use electricity in the junior high school physics, some students still do not understand the reason why the metal shell of the household electrical appliance should be grounded. The main reason is that students cannot fully understand the causes of electric shock accidents. In the teaching practice, I think that using the graphic method to simplify and explain the relevant issues, the effect is indeed good. 1. If the metal shell is not grounded. The insulation of the live wire inside the household appliance is damaged or loses its insulation properties, resulting in the connection of the fire wire and the housing, and the shell is charged. Then the person standing on the ground (assuming that