Uses of Static Electricity

Even though static electricity can be unsafe, it has some uses as discussed below:

• In vehicles spark plugs ignite fuel injected into the engine’s cylinders.
• Copier machines use static electricity. To produce a copy, most modern copier machines make a “charged image” of the original document. The process starts with a uniformly charged belt or drum covered with a photoconductor, which is a material sensitive to light. The machine exposes the original document to a bright source of light; the white parts of the document reflect a lot of this light, and the dark parts reflect only a little. This reflected light is focused on the photoconductor, and in places where the light is strong, the charge on the photoconductor disappears, as the light makes the material conduct and carry away the charges. This does not affect the remaining areas, which correspond to the dark areas of the original, so they continue to be charged. The photoconductor sheet, now charged only in the places corresponding to the dark areas of the original document, contains the charged image. Next the machine applies ink, or toner, to the charge image to make it become visible. The toner has a charge opposite that of the charged image. Electrostatic forces now come into play for when the toner meets the charged image, it sticks to the charged areas (which correspond to the dark areas of the original), because opposite charges attract. The system removes any excess charge and transfers the toner to a sheet of paper. After an application of heat to fuse the toner onto the paper, out comes the duplicate.
• Electrostatic forces are also used when coating objects with a sprayed material through an induction effect. The induction effect can be explained as follows: If a strongly charged object is placed beside an electrically neutral object, it will attract the charges in the neutral object that have opposite sign and repel those that have the same sign, as a result the opposite charges move closer and the same-sign charges move in the other direction. Induction creates, or induces, the uneven distribution of charges in the neutral object.
• Electrostatic induction is used in crop dusters. Crop dusters spray insecticide on farmland from planes or trucks and small drops of the material become charged by friction as they leave the nozzle of the spray gun. Because of the induction, the drops tend to stick to leaves and stems, not just on top but also underneath and on all sides. The spraying therefore fully covers the plants, so they are better protected from the insects.

Electrostatic induction can also be applied to spread paint evenly on a surface. Tiny droplets of paint, when given the same charge, repel one another. When sprayed on a surface, such as the body of a car, the paint forms a smoother coating.

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