Meadowcroft, Wm. H. (William Henry), b. 1853 · New York & London, Harper & brothers · leaf 59
s of this wireare to be attached to the battery. On top of, or over, this primary coil we wrap a greatmany turns ofvery fine wire, ofwhich, as it is sofine, a greatlength can beused. This isFig. 9 called the second- ary coil, and it isin this coil that the volts, or pressure, of elec-tricity become… … THE TELEPHONE the iron core. This armature is made a partof the wire leading to the primary coil. Whenthe current from the battery is sent throughthe wires, the core becomes magnetized anddraws this armature away from a fixed con-tact point, thus breaking the circuit, butthe spring pulls it back,…
Electricity
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