Van de Graaff Generator Experiments
Lightning is the electronic discharge between particles in the air and clouds and the ground. Electricity is carried through current, or the flow of electrons, and lightning is caused by very large currents, which is why it can be so deadly when it strikes. Large currents that cause lightning also cause high voltages. Voltage is the “potential difference” between two places, meaning it describes the ability and likelihood of electric charge to flow from one place to another. If current is relatively low, voltage can be very high and still very safe. The Van de Graaff generator in this experiment operates at high voltages but low currents, similar to the static electricity you experience after rubbing your shoes on carpet and touching a doorknob on a dry day.
You may have seen a Van de Graaff generator in a science museum before. It is an electrostatic generator, and creates static electricity by building up very large voltages on its surface by moving a belt over a terminal and the electric charge accumulates on the surface of a hollow metal sphere. These spheres can hold high enough potential differences to produce a visible spark when objects are brought close. A small, table-top generator can get up to 100,000 V (volts)! One in a museum can get up to 5 megavolts—that’s 5,000,000 V! This is much higher than a typical battery, which is about 1.5 V. This apparatus was invited in 1929 by Robert Van de Graaff, an American scientist.
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