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滑动变阻器是中学物理实验中常用的电学仪器。一般是用来为实验提供可变电阻,从而调节电路中的电流和调节电路中任意两点间的电压。笔者为了克服实验仪器不足的困难和提高仪器的利用率,曾用滑动变阻器来演示“左手定则”收到了很好的实验效果。其具体做法是:将两个小型的滑动变阻器(如 J2354型2A10Ω)平行放置在桌上(将滑动头移到同一端),在两滑动杆上横放一根空心圆筒(圆筒用香烟盒内的锡箔或铝箔卷制,如果用收音机或电视机的坏天线做最好,其外径以5—
Slide rheostats are commonly used electrical instruments in middle school physics experiments. It is generally used to provide a variable resistor for the experiment to regulate the current in the circuit and adjust the voltage between any two points in the circuit. In order to overcome the difficulty of the lack of experimental instruments and improve the utilization of the instrument, the author used the sliding rheostat to demonstrate the “left-hand rule” and received good experimental results. The specific method is: Place two small sliding rheostats (such as J2354 type 2A10Ω) on the table in parallel (move the sliding head to the same end), and place a hollow cylinder (cylindrical cigarette) on both slide bars. The tin foil or aluminum foil in the box is rolled up. If it is best to use a bad antenna on a radio or television, its outer diameter is 5—