Electromagnetic theory of the telephone receiver: With special reference to motional impedance

The theory of the telephone receiver here offered is based upon the motional impedance circle which has been published in various chapters during the last few years. The new theory, which is stated under definite limitations, is a further development; taking into account the m.m.f. produced by the vibration of the diaphragm in the permanent magnetic field. The motional power is thus shown to be derived partly from the testing alternating current and partly from changes in power expended in the magnetic circuit. The motional impedance circle may therefore also be regarded as a power circle, with components along three different axes of reference.