Magnetism

Chapter Magnetism

Teach Yourself Electricity and Electronics Third Edition Book
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Summary of Contents

Teach Yourself Electricity and Electronics Third Edition Book

  • 8CHAPTERMagnetismTHE STUDY OF MAGNETISM IS A SCIENCE IN ITSELF. ELECTRIC AND MAGNETIC phe-nomena interact; a detailed study of magnetism and electromagnetism could easily filla book. Magnetism was mentioned briefly near the end of chapter 2. Here, the subjectis examined more closely. The intent is to get you familiar with the general concepts ofmagnetism, insofar as it is important for a basic understanding of electricity and elec-tronics.The geomagnetic fieldThe earth has a core made up largely of iron, heated to the extent that some of it is liq-uid. As the earth rotates, the iron flows in complex ways. It is thought that this flow isresponsible for the huge magnetic field that surrounds the earth. The sun has a mag-netic field, as does the whole Milky Way galaxy. These fields might have originally mag-netized the earth.Geomagnetic poles and axisThe geomagnetic field, as it is called, has poles, just as a bar magnet does. These polesare near, but not at, the geographic poles. The north geomagnetic pole is located in thefrozen island region of northern Canada. The south geomagnetic pole is near Antarc-tica. The geomagnetic axisis somewhat tilted relative to the axis on which the earthrotates. Not only this, but it does not exactly run through the center of the earth. It’s likean apple core that’s off center.The solar windThe geomagnetic field would be symmetrical around the earth, but charged particles fromthe sun, constantly streaming outward through the solar system, distort the lines of flux.134Copyright © 2002, 1997, 1993 by The McGraw-Hill Companies. Click here for terms of use.