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“把电流表改装为电压表”是高中物理电学实验中较难的一个学生实验。要把电流表改装为电压表,首先要知道电流表的三个主要参数:电流表指针偏转到最大值时的电流,称为满偏电流 I_g,即为允许通过电流表的最大电流,可以从表盘上直接读出;电流表内阻 R_g,可以用实验方法测出;满偏时电流表两端的压降称为满偏电压 U_g,三者之间的关系是:U_g=L_g×R_g。该实验首先需要测出 R_g,方能进行电表的改装。我在多年的教学实践中,总结了几种测量 R_g的方法,供大家参考。
The “converting an ammeter into a voltmeter” is a difficult student experiment in high school physical electrical experiments. To convert an ammeter into a voltmeter, first of all, you must know the three main parameters of the ammeter: the current when the ammeter pointer is deflected to the maximum value, which is called the full bias current I_g, which is the maximum current allowed through the ammeter and can be read directly from the dial. Out; current meter internal resistance R_g, can be measured by the experimental method; full deflection when the voltage drop across the ammeter is called full voltage U_g, the relationship between the three is: U_g = L_g × R_g. The experiment first needed to measure R_g to be able to modify the meter. In my teaching practice for many years, I summarized several methods for measuring R_g for your reference.