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在用万用电表测量电阻的问题中涉及到对于某一定值的电阻,究竟应该选用哪一档来进行测量。正确的方法是选用中值电阻与待测电阻相近的那一档,这样测量的误差才比较小。但是不少学生对其原因搞不清楚。此外,“相近”这个词比较含糊,究竟在什么范围内就能认为是相近的呢?本文就上述问题谈一点教学中的体会。首先要对学生讲清:用万用电表测一个待测电阻R_x,当R_x有某一个变化量ΔR_x时,通
The problem of measuring the resistance with a multimeter involves the choice of which gear to use for a given value of resistance. The correct method is to use the same median resistance and the resistance to be measured, so that the measurement error is relatively small. However, many students are not clear about their reasons. In addition, the word “similar” is vague. In what context can we think of it as similar? This article discusses the above-mentioned problems in teaching. First, explain to the students: Use a multimeter to measure a resistance R_x to be measured. When R_x has a certain amount of change ΔR_x,