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在进行初中物理课“高压送电”一节的教学时,差不多每次都要遇到一个共同性的问题,那就是在学完这一节之后,学生容易“发叉”,自己推出一个与实际情况完全相反的结论。初中物理教材在讲述远距离送电要升高电压时是这样论述的:“从焦耳—楞次定律的公式 Q=0.24I~2Rt 来看,……要减少输电线路上的电能损耗,可以……减少线路中的电流强度,……根据电功率公式 N=IV,在保持功率不变的前提下,要减小输电线路中的电流强度,必须升高输电电压。这就是采用高压输电的道理。”(山东省初中课本((物理》1975年版)有些学生在学完这节内容后,结合以前学过的欧姆定律公式,便会进行如下的推论:因
When teaching in the High Voltage Power Delivery section of the junior high school physics class, there is a common problem almost every time, that is, after completing this section, students are easy to “fork” and introduce themselves to the actual The opposite is true. Middle school physics textbooks telling long-distance power transmission to raise the voltage is such a discussion: "From Joule - Lenz’s formula Q = 0.24I ~ 2Rt point of view, ... ... to reduce transmission line power loss, you can ... ... Reduce the current intensity in the line, ... According to the formula of electric power N = IV, in order to reduce the current intensity in the transmission line while keeping the power unchanged, it is necessary to increase the transmission voltage. (Textbook of Shandong Junior High School (Physics, 1975.) Some students, after completing this section, combined with the previously learned Ohm’s Law formula, make the following corollary: