Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . ron, C, is sup-ported by a brass pieceextending across thepole pieces. The ironcylinder is smaller indiameter than the boreof the pole pieces, sothat the magnetic linesof force pass acrossthis air gap, makinga very strong and uni-form magnetic movable systemis shown in Fig. 198. It consists of a rectangular coil of wire,wound upon a bobbin of thin sheet copper or aluminum anddelicately suspended be-tween jewel terminals of the coilare connected to the hori-zont
Lessons in practical electricity; principles, experiments, and arithmetical problems, an elementary text-book . ron, C, is sup-ported by a brass pieceextending across thepole pieces. The ironcylinder is smaller indiameter than the boreof the pole pieces, sothat the magnetic linesof force pass acrossthis air gap, makinga very strong and uni-form magnetic movable systemis shown in Fig. 198. It consists of a rectangular coil of wire,wound upon a bobbin of thin sheet copper or aluminum anddelicately suspended be-tween jewel terminals of the coilare connected to the hori-zontal spiral springs,against which the coilacts when it tends torotate, the springs serv-ing to also conduct thecurrent to and from thecoil. A thin aluminumknife-edge pointer at-tached to the bobbin andswinging over the scale,Fig. 195, indicates theangle of deflection of thecoil. This coil is mountedconcentrically with theiron cylinder and polepieces in the air gap, asShown in Fig. 196, where Fig. Ammeter with Cover Re- . o .-I - i • moved Snowing D Arsonvai part 01 the pole piece, AMMETERS. 205 etc., have been cut away. When a current is sent throughit, by the springs, the coil tends to move through themagnetic field, to take up a position so that its lines of forcewill be in the same direction as those of the field. Itwill so move until the torsion of the springs is balancedby the force tending to move the coil, when the pointerwill indicate the angle of deflection. The angle of deflec-tion is nearly proportional to the current throughout themovement, which £-ives a very uniform scale, as can be seenfrom Fig. 195. The metallic bobbin on which the coil is
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1901
