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现行初中课本“物理”第二册第200页,练习三第(1)题,“将长度和横截面积完全相等的镍铬合金丝和铁丝照图9-8甲如附图所示串联在电路中,在镍铬合金丝和铁丝下面用蜡(或凡士林)粘上几根火柴,当接通电源后,哪些火柴先掉下来?为什么?……”附图该题的原意是巩固焦耳定律知识,然而却带来了副作用。容易使学生对温度和热t这两个不同的物理概念产生混淆。从学生回答的情况来看,一般都回答是:按图甲那样连接,镍铬合金丝上的
Current junior high school textbook “Physics ” second volume, page 200, practice three (1), “ nickel-chromium alloy wire and iron wire with the same length and cross-sectional area according to Figure 9-8. Indicated in series in the circuit, in the nickel-chromium alloy wire and under the wire with wax (or Vaseline) stuck a few matches, when the power is turned on, which match first drop? Why? ... ” The figure of the original intention of the title It is to consolidate knowledge of Joule's law, but it has brought about side effects. It is easy for students to confuse the two different physical concepts of temperature and heat. From the student's answer, the general answer is: Connect as in Figure A, on the Nichrome wire