Basic electrical engineering with numerical problems (vol 1) part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Basic electrical engineering with numerical problems (vol 1) part 2
Basic electrical engineering with numerical problems (vol 1) part 2
6Magnetism, Electromagnetism and Electromagnetic Induction6 1 MAGNETMagnet is ii piece of ferromagnetic or ferrimagnetic material substance which has Basic electrical engineering with numerical problems (vol 1) part 2 the property of attracting iron, nickle and cobalt.6.2 CLASSIFICATION OF MAGNETSThe main classes of magnets arc as follows:(f) Natural magnet, and(//) artificial magnet.Natural Magnet The term “lodestone” was first applied to a hard black mineral stone found in Magnctia, a province in Asia. Lodesto Basic electrical engineering with numerical problems (vol 1) part 2ne possesses the property of attracting small pieces of iron and points along the northsouth direction when hung freely by a thread-Later, this stoneBasic electrical engineering with numerical problems (vol 1) part 2
began to be known as magnetite and due to its property of attracting iron, it is now more popular by the name of “magnet.”If a lodestone is dipped int6Magnetism, Electromagnetism and Electromagnetic Induction6 1 MAGNETMagnet is ii piece of ferromagnetic or ferrimagnetic material substance which has Basic electrical engineering with numerical problems (vol 1) part 2joining the poles is known as the ‘'magnetic axis”. If the lodestone is suspended freely, itFig. 6.1 Natural magnetwill so adjust itself that the magnetic axis almost coincides with the geographical meridian. The poles which point north and south are respectively called north-seeking and south-seeki Basic electrical engineering with numerical problems (vol 1) part 2ng poles. In short, the northseeking pole is known as the north pole and the south-seeking pole as the south pole.A substance which possesses these twBasic electrical engineering with numerical problems (vol 1) part 2
o properties, namely of attracting iron fillings and pointing in the direction of north and south when freely suspended is called a magnet. The lodest6Magnetism, Electromagnetism and Electromagnetic Induction6 1 MAGNETMagnet is ii piece of ferromagnetic or ferrimagnetic material substance which has Basic electrical engineering with numerical problems (vol 1) part 2l which have been magnetised by artificial method and is known as artificial magnet.6.3 CLASSES AND SHAPES OF ARTIFICIAL MAGNETThe artificial magnets can be divided into two classes as:(/) Permanent magnet(//) Temporary magnet.permanent Magnet Permanent magnets arc made of steel and retain magnetism Basic electrical engineering with numerical problems (vol 1) part 2 (i.e., the property of attracting iron) for a long time. They are generally made as bar magnets, horse-shoe magnets, ư-shapcd magnets and cylindricalBasic electrical engineering with numerical problems (vol 1) part 2
magnets, as shown in Fig. 6.2. The material used for making permanent magnets is either cobalt, steel or tungsten steel.Uses of Permanent Magnet Bar 6Magnetism, Electromagnetism and Electromagnetic Induction6 1 MAGNETMagnet is ii piece of ferromagnetic or ferrimagnetic material substance which has Basic electrical engineering with numerical problems (vol 1) part 2ng deflecting torque. They are also provided in an energy meter as a brakingSI Basic Electrical EngineeringMAGM 'Fig. 6.2 Types of artificial magnetthem. But if two south poles are brought near each other, they repel. The same happens in the case of two north poles. This means that (0 like poles rep Basic electrical engineering with numerical problems (vol 1) part 2el each other and (//) unlike poles attract each other.From the above it is clear that a magnet attracts pieces of iron or Steel but repels only magneBasic electrical engineering with numerical problems (vol 1) part 2
ts. Therefore repulsion is a sure test of magnetism.6.5 METHODS OF MAGNETIZATIONThere are three principle methods of magnetizing a steel bar as given 6Magnetism, Electromagnetism and Electromagnetic Induction6 1 MAGNETMagnet is ii piece of ferromagnetic or ferrimagnetic material substance which has Basic electrical engineering with numerical problems (vol 1) part 2kers, moving coil instruments, microphones, car phones magnetic needles, etc. They are also used for navigation purposes.Temporary Magnets All electromagnets are temporary magnets. These arc made by sending á current through a wire wound around a piece of iron and remain magnetic(i)Touch method This Basic electrical engineering with numerical problems (vol 1) part 2 method can be further divided as r(o) Single touch method,(b)double touch method, and(c)divided touch method.(a) Single Touch Method In the single toBasic electrical engineering with numerical problems (vol 1) part 2
uch method, the Steel bar to be magnetized is rubbed with either of the poles of H magnet, keeping the other pole away from it. RubbingN./././//56Magnetism, Electromagnetism and Electromagnetic Induction6 1 MAGNETMagnet is ii piece of ferromagnetic or ferrimagnetic material substance which has 6Magnetism, Electromagnetism and Electromagnetic Induction6 1 MAGNETMagnet is ii piece of ferromagnetic or ferrimagnetic material substance which hasGọi ngay
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