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近几年来,为了降低初高中物理知识点的衔接梯度,各地在中考题中适当地渗透了高中的电源及电表的内电阻问题。笔者通过对中考题中相关典型例题的解读,就该类问题进行归类分析。一、测量电源电压及内电阻的问题实际上,电源内部都是有电阻的(图1-a)。测量电源内电阻时,为了研究问题的方便我们可以建立一个物理模型,将电路中的实际电源分解成两部分:一是将电源看成是一个无电阻(电阻为0),电压为U
In recent years, in order to reduce the connection gradient of physics knowledge in junior and senior high schools, all parts of the middle school entrance examination questions have properly penetrated the problem of the internal resistance of the power supply and ammeter in senior high schools. The author through the interpretation of the relevant typical examples in the examination questions, the classification of such issues. First, the measurement of the power supply voltage and the resistance problem In fact, the internal power supply is a resistance (Figure 1-a). To measure the internal resistance of the power supply, in order to study the convenience of the problem, we can establish a physical model, the actual power supply circuit is divided into two parts: First, the power supply as a no resistance (resistance 0), the voltage U