Edited by Jamie (ScienceAid Editor), Administrator, Taylor (ScienceAid Editor)
Electric charge is a fundamental property of matter. The most common charged particles are electrons (negative) and protons (positive) which are oppositely charged particles in the atom. Oppositely charged particles attract and like charges repel.
Materials which conduct electricity are metals (iron, copper, aluminum, etc.) and also carbon - in the form of graphite. All other types of material are electric insulators. meaning you cannot pass an electric current through them, however, these insulating materials (like plastic) can be charged by friction. This is because the material is either loosing or gaining electrons. The electrons will go from one item to another.
This charging of insulative materials can be seen everyday. For example, when you pull your sweater over your head, and hear the familiar crackling, and your hair ends up standing on end - all because your hair has rubbed against your sweater. You can also get shocked by the rubber handrail of an escalator, even though rubber is an insulator, because it has gradually become charged from the constant motion creating friction. The diagram below shows how electrons are transferred when you rub a balloon against some fabric.
This electrostatic charge can have some serious repercussions. When an aircraft is being refuelled, the friction causes charge separation: where the aircraft has an opposite charge to the fuel. If the voltage becomes high enough it may cause a spark. Igniting the fuel and causing a fire.
To prevent the framework from building up charge, it is connected to earth (also called grounding or ground), so that any charge can disperse, and fire is prevented.
As well as dangers, electrostatic charge has many uses. A common one is in painting metals to create a smooth, even spread of paint. As paint comes out of a nozzle it is positively charged. This causes the droplets to separate and spread out because like charges repel. The metal plate is earthed (grounded), and electrons flow from earth causing it to become negatively charged. The paint is attracted to the metal because opposite charges attract so there is an even coverage.
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Categories : Electricity
Recent edits by: Administrator, Jamie (ScienceAid Editor)