Subharmonic frequencies produced in non-linear systems

Measurement of relative and true power factors of air capacitors

“…There is also a possibility that harmonics which may be present in the current from the source will combine in the amplifier to produce a fundamental which would in turn cause a deflection on a tuned indicator, even though the bridge were perfectly balanced for the fundamental frequency. This latter effect has been shown analytically by Goodhue [9] and experimentally by Ferguson and Bartlett [10] as well as during the course of this work. For this also a null indication would require an off-balance condition in the bridge for neutralization.…”