The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 21
wire. This ironplate, or diaphragm, usually of ferrotype, is made very Ihin, so as to beflexible. Sound waves impinging upon this diaphragm result in movementor vibration, and this movement causes an alteration in the distribution ofthe lines of force in the magnetic field. The coil of wire is so… … Every movement of the diaphragm causes an electric current. Themagnetic field will be disturbed to the greatest extent at or near thepoles of the magnet: consequently, the coil of wire is made to surroundone pole of the magnet (as shown in Figure 2). The lines we may imagineas moving laterally…
Telephone · Postal service
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