An elementary book on electricity and magnetism and their applications . The twogreat experimenters also independently discovered the factthat any change in the magnetic field around a wire tends to setup an electric current in the wire; exactly as any change in anelectric current which flows in a wire causes a correspondingchange in the magnetic field about it. In this great discovery lies the principle of the operation ofdynamo electric generators or generators, as they are usuallycalled. It must not be forgotten, however, that there is a vast differencebetween discovering a new principle, s
An elementary book on electricity and magnetism and their applications . The twogreat experimenters also independently discovered the factthat any change in the magnetic field around a wire tends to setup an electric current in the wire; exactly as any change in anelectric current which flows in a wire causes a correspondingchange in the magnetic field about it. In this great discovery lies the principle of the operation ofdynamo electric generators or generators, as they are usuallycalled. It must not be forgotten, however, that there is a vast differencebetween discovering a new principle, such as that of electromag-netic induction, and building a commercially efficient machine,such as the electric generator, which utilizes the principle. Ittakes a genius to develop a new principle, but it often requiresyears of patient experimenting by a multitude of inventors toperfect the machine. Sometimes it takes so long to apply theprinciple that the public has quite forgotten who discovered itand rewards only the inventor who has made the machine go. PLATE Joseph Henry (1799-1878). An American physicist, born in Albany, New York; was for six years a school-master at Albany Academy, for fourteen years a professor at Princeton, andfor the rest of his life the head of the Smithsonian Institution in the first careful study of the electromagnet and in 1842 discovered theoscillatory nature of the electric spark. Shares with Faraday the honor ofhaving discovered the laws of electromagnetic induction. ELECTROMAGNETIC INDUCTION 139
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmagnetism, bookyear19
