论文部分内容阅读
在现行高二物理甲种本第二册238页气体的导电性这一节教材中,为了说明空气在特定的情况下可以变成导体,专门安排了如附图(a)的实验。可是在我们潮湿的南方,特别是教材又安排在春季,要想顺利地完成这一实验就难了。关键是空气潮湿,为此,我们通过实践,改用平行板电容器(φ=200mm)、教学用高压电源(直流250V—300V)和 j0403教学演示电表(表板面取直流50—0—50μA档)按附图(b)联接好电路,使平行板电容器两板间的距离等于15mm左右;接通电源,用酒精灯火焰置于二平行板之间下方,这时,可以看到电流表指针迅速偏转,(7μA左右)表明平行板之间的空气已导电了,空气变成了导体。为了增大实验的可见度,在电路中安装一个简单的放大器(本章第十三节马上就要讲到的内容),实验效果更为显著,具体安装如附图(c),三极管选用穿透电流小于1μA的3DG12B(或C),β值大于70的管子,电流表板面取直流1mA为宜。在接线的过程中要尽量使之接触良好,
In the present textbook of the current “Study on the Conductivity of Gases” in the second edition of the second edition of the Physics Book on page 238, in order to show that air can become conductors under certain conditions, the experiment as shown in Figure (a) is specifically arranged. But in our wet South, especially the textbooks are arranged in the spring, it is difficult to successfully complete this experiment. The key is air humidity. For this reason, through practice, we switched to using parallel plate capacitors (φ=200mm), teaching high-voltage power supplies (DC 250V to 300V) and j0403 teaching demonstration electricity meters (taken from 50-50μA DC ) Connect the circuit according to the drawing (b) so that the distance between the two plates of the parallel plate capacitor is equal to about 15mm; turn on the power and place the flame between the two parallel plates with the flame of the alcohol lamp. At this moment, you can see the current meter pointer quickly. The deflection, (about 7 μA), indicates that the air between the parallel plates has been conducting and the air has become a conductor. In order to increase the visibility of the experiment, a simple amplifier is installed in the circuit (the content to be mentioned in the thirteenth chapter of this chapter), and the experimental effect is more obvious. The specific installation is as shown in the figure (c). The transistor uses a penetrating current. For 3DG12B (or C) less than 1μA, tubes with a β value greater than 70, a DC current of 1mA is appropriate for the ammeter board. In the process of wiring, try to make it in good contact.