Cells and batteries

Chapter Cells and batteries

Teach Yourself Electricity and Electronics Third Edition Book
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Summary of Contents

Teach Yourself Electricity and Electronics Third Edition Book

  • 7CHAPTERCells and batteriesONE OF THE MOST COMMON AND MOST VERSATILE SOURCES OF DC IS THE CELL.The term cell means self-contained compartment, and it can refer to any of various dif-ferent things in (and out of) science. In electricity and electronics, a cell is a unit sourceof dc energy. There are dozens of different types of electrical cells.When two or more cells are connected in series, the result is known as a battery.Kinetic and potential energyEnergy can exist in either of two main forms. Kinetic energy is the kind you probablythink of right away when you imagine energy. A person running, a car moving down afreeway, a speeding aircraft, a chamber of superheated gas—all these things are visiblemanifestations of kinetic energy, or energy in action. The dissipation of electrical power,over time, is a form of kinetic energy too.Potential energy is not as vividly apparent. When you raise a block of concrete intothe air, you are creating potential energy. You remember the units called foot pounds,the best way to measure such energy, from school physics classes. If you raise aone-pound weight a foot, it gains one foot pound of potential energy. If you raise it 100feet, it gains 100 foot pounds. If you raise a 100-pound weight 100 feet, it will gain 100× 100, or 10,000, foot pounds of potential energy. This energy becomes spectacularlyevident if you happen to drop a 100-pound weight from a tenth-story window. (But don’t!)Electrochemical energyIn electricity, one important form of potential energy exists in the atoms and moleculesof some chemicals under special conditions.Early in the history of electrical science, laboratory physicists found that when118Copyright © 2002, 1997, 1993 by The McGraw-Hill Companies. Click here for terms of use.