St. John, Thomas M. (Thomas Matthew), b. 1865 · New York, T. M. St. John · leaf 103
Fig. 134- lOO HOW THU TELEPHONE TRANSMITS SPEECH. … Fig. 135- is used to transform the batterycurrent, that flows through thecarbon transmitter and primarycoil, into a current with a highE. M. F. The battery currentin the primary coil is undula-ting, but always passes in thesame diredlion, making themagnetic field around the coreweaker and stronger.…
Electricity
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