An elementary book on electricity and magnetism and their applications . since their time many improve-ments have beenmade and it iscontinually beingperfected. 140. A simplegenerator. If aclosed coil of wiremounted on anaxis or shaft is re-volved as in figure130, an alternatingcurrent is produced, which has been described in section 105. If, instead of being short-circuited on itself, the coil is con-nected with an external circuit by means of such sliding con-tacts as are shown in figure 131, thealternating current may be led off tobe used for any desired purpose. Therings A A, to which the e
An elementary book on electricity and magnetism and their applications . since their time many improve-ments have beenmade and it iscontinually beingperfected. 140. A simplegenerator. If aclosed coil of wiremounted on anaxis or shaft is re-volved as in figure130, an alternatingcurrent is produced, which has been described in section 105. If, instead of being short-circuited on itself, the coil is con-nected with an external circuit by means of such sliding con-tacts as are shown in figure 131, thealternating current may be led off tobe used for any desired purpose. Therings A A, to which the ends of the coilsare attached, are in this case called col-lecting rings, and the parts BB, whichbear on the collecting rings, are calledbrushes. In an actual machine madeup for the purpose of generating elec-tricity by a coil revolving in a magnetic attached to diding ringsfield, the revolving part is called an A\. with ,u;lus ** ° l , making connection witn armature. Telephone magnetos, which external circuit. Fig. 130. Coil arranged to be rotated in DIRECT-CURRENT GENERATORS 201 are used for ringing telephone call bells, are small alternating-current generators; each consists of a coil of wire wound on aniron core which is revolved in the magnetic field between thepoles of a permanent horse-shoe magnet. In the Ford magnetowe have a series of horse-shoe steel magnets attached to theflywheel so that their poles move rapidly past stationary coils(Fig. 92) in which the alternating electric current is we have a moving magnetic field and stationary armaturecoils. 141. Commutator. To get a direct current or continuouscurrent, that is, one which flows always in the same direction,we have to use a commu-tator. To understand howthis works let us study avery simple case. If theends of the loop in section140 are connected with asplit ring, as shown in figure132, we may set the brushesB-\- and B— on oppositesides of the ring so thateach brush will connect
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmagnetism, bookyear19
