Magnetic force

Chapter Magnetic force

Teach Yourself Electricity and Electronics Third Edition Book
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Teach Yourself Electricity and Electronics Third Edition Book

  • This solar wind literally “blows” the geomagnetic field out of shape, as shown in Fig. 8-1.At and near the earth’s surface, the lines of flux are not affected very much, and the geo-magnetic field is nearly symmetrical.Magnetic force1358-1The geomagnetic field is distorted by the solar wind.The magnetic compassThe presence of the geomagnetic field was first noticed in ancient times. Some rocks,called lodestones, when hung by strings would always orient themselves a certain way.This was correctly attributed to the presence of a “force” in the air. Even though it wassome time before the details were fully understood, this effect was put to use by early sea-farers and land explorers. Today, a magnetic compass can still be a valuable navigationaid, used by mariners, backpackers, and others who travel far from familiar landmarks.The geomagnetic field and the magnetic field around a compass needle interact, sothat a force is exerted on the little magnet inside the compass. This force works not onlyin a horizontal plane (parallel to the earth’s surface), but vertically at most latitudes.The vertical component is zero only at the geomagnetic equator, a line running aroundthe globe equidistant from both geomagnetic poles. As the geomagnetic lattitude in-creases, either towards the north or the south geomagnetic pole, the magnetic forcepulls up and down on the compass needle more and more. You have probably noticedthis when you hold a compass. One end of the needle seems to insist on touching thecompass face, while the other end tilts up toward the glass. The needle tries to align it-self parallel to the magnetic lines of flux.Magnetic forceMagnets “stick” to some metals. Iron, nickel, and alloys containing either or both of theseelements, are known as ferromagnetic materials. When a magnet is brought near a piece