2015+1-1,2,3+all.pdf

# Although scientists could not explain static

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Although scientists could not explain static electricity for centuries, engineers realized that it presented a serious industrial problem. For example: Ø As early as the 1400’s, European and Caribbean forts were using static control procedures and devices to prevent electrostatic discharge ignition of black powder stores [1]. Ø By the 1860's, paper mills throughout the U.S. employed basic grounding, flame ionization techniques, and steam drums to dissipate static electricity from the paper web as it traveled through the drying process [1]. Today, the challenge of removing static electric charges from workplace is more important than ever, because static electricity easily damages electronic equipment and accounts for huge annual losses in industry. T HE NATURE OF STATIC ELECTRICITY According to today’s views, there are two types of electric charges, called positive and negative. The elementary positive charge (of a proton) equals 1.602 · 10 -19 C, where C stands for coulomb – the SI unit of charge named after French scientist Charles-Augustine de Coulomb (1736 -1806). [See Appendix 1 for more information on the units of measure.] The elementary negative charge (of an electron) has the exactly same magnitude. This magnitude is extremely small: for example, the current through a hair dryer carries ~10 20 elementary charges per second. <Sidebar> The elementary positive charge (of a proton) equals 1.602 · 10 -19 C. The elementary negative charge (of an electron) has the exactly same magnitude. Electric charges of opposite signs attract each other; charges of the same sign repel each other (recall the Coulomb’s law). The forces between electric charges are relatively strong: they hold together atoms and molecules, solid bodies and fluids. As we know today, all materials are built of atoms; each atom has a positively charged nucleus (radius from 1 to 10 fm, depending on the chemical element) surrounded with a “cloud” of negatively charged electrons (radius from 30 to 300 pm, that is ~30,000-fold larger than the nucleus). Usually, each atom is electrically neutral: the number of protons in the nucleus is exactly equal to the number of electrons. However, atoms are not always electrically neutral: under certain conditions, an atom can either lose one or more electrons and become a positive ion, or acquire one or more extra electrons and become a negative ion. If these surplus electric charges are not moving right away, we call them static electric charges. Thus a positive static charge is due to lack of electrons, and a negative static charge is due to an excess of electrons. Book Page 126

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EE for 21 st century 1-3 Prevent electrostatic discharge 1-3-1 Hazards of ESD for EE © 2015 Alexander Ganago Page 4 of 23 Last printed 2015-07-24 6:00 PM File: 2015 1-3-1 ESD.docx One of the fundamental principles of this Universe is the conservation of electric charges: in any closed system, the net electric charge is conserved.
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• Fall '07
• Ganago
• Electric charge, Alexander Ganago

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