. The principles of physics. o the use to be made of them. If we wish, as inthe experiments already described, to use but a single pole,it is desirable to have the other as far away as possible;then, obviously, the bar magnet is most convenient. But ifthe magnet is to be used for lifting or holding weights, theU-form is far better, because the attraction of both polesis conveniently available. Magnets, • when not in use, oughtalways to be protected by armatures (A, Fig. 404) of softiron; for, notwithstanding the retentivity ofsteel, they slowly part with their when an armature is
. The principles of physics. o the use to be made of them. If we wish, as inthe experiments already described, to use but a single pole,it is desirable to have the other as far away as possible;then, obviously, the bar magnet is most convenient. But ifthe magnet is to be used for lifting or holding weights, theU-form is far better, because the attraction of both polesis conveniently available. Magnets, • when not in use, oughtalways to be protected by armatures (A, Fig. 404) of softiron; for, notwithstanding the retentivity ofsteel, they slowly part with their when an armature is used, the opposite polesof the magnet and armature being in contactwith each other, N with S, they serve to bindeach others magnetism. Thin bars of steel canbe more thoroughly magnetized than thick , if several thin bars (Fig. 404) be laid sideby side, with their corresponding poles turned inthe same direction and then screwed together, avery powerful magnet is the result. This is called a com-pound Fig. 404. MAGNETIC LIKES OF FOEOE. 523 Section XIV. MAGNETIC LINES OF FORCE. THE MAGNETIC CIRCUIT. 491. Magnetic lines of force. — These lines are easilystudied by the use of iron filings. The field of force arounda magnet is shown Hi by placing a paperover it, dustingfilings upon thepaper, and tappingit. The filingstake symmetricalpositions, formcurves between thepoles of the mag-net or magnets,and show that thelines of force con-nect the oppositepoles of the m,ag-net. The fact is, that each filing, when brought within theinfluence of the magnetic field, becomes a magnet by induc-tion, and of necessity tends to take a definite position which
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysics, bookyear1895
