. Practical wireless telegraphy; a complete text book for students of radio communication . ar coil of fine wire, A, B,is mounted on the metal bobbin G. It issupported by jewelled bearings and heldin the zero position of the scale by thespiral springs, S-1 and S-2, throughwhich the circuit of the coil is com-pleted. When the pointer is in zero po-sition, the coil rests at a slight angle tothe pole pieces of a permanent magnet,N, S. When current is flowing throughthe coil, the normal field from N to S islengthened out and in trying to shortenthemselves, the lines of force actuallytwist or turn
. Practical wireless telegraphy; a complete text book for students of radio communication . ar coil of fine wire, A, B,is mounted on the metal bobbin G. It issupported by jewelled bearings and heldin the zero position of the scale by thespiral springs, S-1 and S-2, throughwhich the circuit of the coil is com-pleted. When the pointer is in zero po-sition, the coil rests at a slight angle tothe pole pieces of a permanent magnet,N, S. When current is flowing throughthe coil, the normal field from N to S islengthened out and in trying to shortenthemselves, the lines of force actuallytwist or turn the coil. When the tensionof the spring is equal to the pull of themagnetic field, the pointer comes to restand the reading of the instrument may thenbe observed. An external resistance coil,R, is connected in series with the windingof the bobbin to reduce the flow of cur-rent to a minimum value. This coil mayhave resistance of 100,000 ohms and maybe provided with two taps making themeter a double scale instrument. essentially no difference inthe construction of the ammeter and. Fig. 47—Mechanism of Voltmeter. AMMETER
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
