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学生在初中学习了测电笔的使用后,在高中阶段的学习中,经常提出下列问题。用测电笔测试火线时,氖管是怎么亮的?测电笔在直流电中有应用吗?实验中能用测电笔判断物体是否带有电荷吗?我利用中学物理实验室中的常用仪器,测试了测电笔中元件的一些电参数,并通过这些参数谈谈自已对以上问题的看法。通常的低压测电笔分为钢笔和螺丝刀式两种,它们都是由笔尖金属体、碳质电阻、氖管、弹簧和笔套及笔尾金属体构成。我用J—T 13调压变压器,CT890数字式电表,500型万用表等仪器测试了从商店里购买的标有“100～1000V”、“100～550V”两种型号的测电笔,测试电原理图如图1所示。将测试元件的电参数列表如下。
After the students studied the use of the test pencil in junior high school, they frequently asked the following questions during the high school study. When using a pencil to test FireWire, how bright is the neon tube? Does the pencil have any application in direct current? Can I use a pencil to determine if an object is charged? I used a common instrument in a middle school physics lab to test it. Some of the electrical parameters of the components in the test pencil, and through these parameters talk about their own views on the above issues. The general low-voltage test pencil is divided into two types of pens and screwdrivers. They are composed of a pen tip metal body, a carbonaceous resistor, a neon tube, a spring and a pen holder, and a pen-tail metal body. I used a J-T 13 voltage regulator transformer, a CT890 digital meter, and a 500-type multimeter to test two types of test pencils labeled “100-1000V” and “100-550V” purchased from a store. The figure is shown in Figure 1. The electrical parameters of the test element are listed below.