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参加第17届“国际科学与和平周”全国中小学(江苏地区)金匙科技竞赛个人决赛的选手,或许还会记起一个有趣的题目,叫“高压人体带电”。首先,让一根导线带上几万伏的高压,演示人员站在绝缘板上,然后很快地用手抓住了高压导线。此时,演示人员手中金属球上的铝箔也张开了,人体已带了几万伏的高压电,然而演示人员毫发无损。问:金箔带子为什么会张开?一般情况下,安全电压是多少?站在绝缘板上的人,手握住导线后为什么是安全的?答:由于铝箔带同种电荷,互相排斥,所以铝箔就张开了;安全电压是不高于36V的电压;站在绝缘板上的人之所以安全,是因为人与导线之间的电势相等(等电位或电势差为零)。
The participants in the 17th “International Science and Peace Week” national primary and secondary school (Jiangsu region) gold spoon science and technology competition finals, may also remember an interesting topic, called “high-voltage human body charged.” First, put a wire with tens of thousands of volts of high voltage. The demonstrator stood on the insulation board and quickly grasped the high-voltage wire by hand. At this point, the aluminum foil on the metal ball in the hands of the demonstrators was also opened, and the human body had taken tens of thousands of volts of high voltage. However, the demonstrator was unscathed. Q: Why is the gold foil tape open? Under normal circumstances, what is the safe voltage? Why do people who stand on the insulation board are safe after holding the wire? A: Since the aluminum foil is charged with the same kind of charge, they are mutually exclusive. It opens; the safe voltage is a voltage no higher than 36V; the person standing on the insulation board is safe because the potential between the person and the wire is equal (equal potential or potential difference is zero).