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“测小灯泡功率”的问题之所以成为中考热点,是因为在题中几乎集中了初中电学的所有重点知识.如串联电路的电流、电压特点,电流表、电压表的使用及读数,电学实验的操作步骤,现象观察,实验故障,滑动变阻器的使用,欧姆定律,电功率的计算,电源的合理选择、表格的设计等.在教学过程中发现,这类题目存在一些共同特点.特点1:这类题目往往伴随着实验过程的部分描述.特点2:这类题目一般会给出额定电压和额定电流,有时也会给出滑动变阻器的最大阻值或是电源电压,有时还会给出额定电功率的范围.
The reason why the problem of “measuring small bulb power” became a hot spot in the examination is because almost all the key knowledge of junior middle school was concentrated in the title, such as the current and voltage characteristics of the series circuit, the use and reading of ammeter, voltmeter, Experimental operation, observation of phenomena, experimental failure, the use of sliding rheostat, Ohm’s law, the calculation of electric power, the rational choice of power supply, the design of the form, etc. During the course of teaching, there are some common characteristics of these kinds of problems.Spectrum 1: These topics are often accompanied by some description of the experimental process Feature 2: These topics generally give the rated voltage and the rated current, and sometimes give the maximum resistance of the sliding rheostat or supply voltage, and sometimes give the rated Range of electrical power.