An elementary book on electricity and magnetism and their applications . efor transforming mechanical energy into electrical energy, orvice versa, by means of electromagnetic induction. If themachine derives its mechanical power from some source out-side of itself, such as a water wheel or steam engine, anddelivers electric power, it is called a generator. If, on theother hand, the electricity is generated outside the machineand is brought to it, and if this power puts the machine inmotion and so runs other machinery, such as a sewing machine orstreet car, the machine is called a motor. The te
An elementary book on electricity and magnetism and their applications . efor transforming mechanical energy into electrical energy, orvice versa, by means of electromagnetic induction. If themachine derives its mechanical power from some source out-side of itself, such as a water wheel or steam engine, anddelivers electric power, it is called a generator. If, on theother hand, the electricity is generated outside the machineand is brought to it, and if this power puts the machine inmotion and so runs other machinery, such as a sewing machine orstreet car, the machine is called a motor. The term dynamo includes both generator and motor. In short, the dynamo isa reversible machine, and the same machine may be drivenpart of the time as a generator and the rest of the time used asa motor to drive another machine; this is sometimes done inshops and often on self-starting automobiles which have but asingle unit. As already stated in Chapter VI, Faraday discovered about1830 that a conductor cutting lines of force, when part of a 199 200 ELECTRICITY AND MAGNETISM. closed circuit, will produce a current. He then constructedcrude machines for utilizing this phenomenon; he may, there-fore, be fairly considered to be the primary inventor of thedynamo. During the following years many investigators,some of whom bear famous names, entered this fascinatingfield of discovery. In the fifties, Siemens, Gramme, and Paci-notti appeared with improvements which developed the dynamointo nearly its present form; 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 desi
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmagnetism, bookyear19
