Take a pocket compass, place it on a table, and watch the needle. It will jiggle around,oscillate, and finally come to rest, pointing more or less north. Therein lie two mysteries.
The first is the origin of the earth’s magnetic field, which directs the needle. The second is the origin of the magnetism of the needle, which allows it to be directed. This book is about the second mystery, and a mystery indeed it is, for although a great deal is known about magnetism in general, and about the magnetism of iron in particular, it is still impossible to predict from first principles that iron is strongly magnetic. This book is for the beginner. By that I mean a senior or first-year graduate student in engineering, who has had only the usual undergraduate courses in physics and materials science taken by all engineers, or anyone else with a similar background. No knowledge of magnetism itself is assumed.
Copyright # 2009 by the Institute of Electrical and Electronics Engineers, Inc.[ 来自科研家族 晶体材料家族 ]

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