. A-B-C of electricity. Fig. 16 ELECTRIC LIGHT more thoroughly when you have finishedreading this little book. Well, you will ask, if we cannot use bat-teries, what is used to produce these electriclights? Machines called dynamo-electric ma-chines, or generators, which are driven bysteam-engines or water-power, are used toproduce the electricity which makes theselamps give us light. You will remember that in the chapteron Magnetism we ex-plained to you howelectricity makes mag-netism, and now wewill explain how, in thedynamo, magnetismmakes electricity. It has been foundthat the influence of a
. A-B-C of electricity. Fig. 16 ELECTRIC LIGHT more thoroughly when you have finishedreading this little book. Well, you will ask, if we cannot use bat-teries, what is used to produce these electriclights? Machines called dynamo-electric ma-chines, or generators, which are driven bysteam-engines or water-power, are used toproduce the electricity which makes theselamps give us light. You will remember that in the chapteron Magnetism we ex-plained to you howelectricity makes mag-netism, and now wewill explain how, in thedynamo, magnetismmakes electricity. It has been foundthat the influence of amagnet is very strongat its poles, and thatthis influence is alwaysin the same lines. Thisinfluence has been de-scribed as lines offorce, which you willsee represented in the sketch above by the dotted lines (Fig. 17). Of course, these lines57. A-B-C OF ELECTRICITY of force are only imaginary and cannot beseen in any magnet, but they are alwayspresent. The meaning of this term lines offorce, then, is used to designate the strengthof the magnet. Many years ago the great scientist Fara-day made the discovery that, by passing aclosed loop of wire through the magneticlines of force existing between the poles of amagnet, the magnetism produced the pecul-iar effect of creating a current of electricityin the wire. If the closed loop of wire werepassed down, say from U to D, the currentflowed in the wire in one direction, and if itwere passed upward, from D to U, the cur-rent flowed in the other direction. Thus,you see, magnetism produces electricity inthe closed loop of wire as it cuts through themagnetic lines of force. Just why or how,nobody knows; we only know that electricityis produced in that way, and to-day we makepractical use of this method of producing itby embodying this principle in dynamo-machines, as we will shortly e
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectelectri, bookyear1915
