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The global electromagnetic resonance phenomenon is named after physicist Winfried Otto Schumann who predicted it mathematically in 1952. Schumann resonances are the principal background in the part of the electromagnetic spectrum [2] from 3 Hz through 60 Hz [3] and appear as distinct peaks at extremely low frequencies around 7.83 Hz (fundamental), 14.3, 20.8, 27.3, and 33.8 Hz.
The fundamental Schumann resonance is at approximately 7.83 Hz, the frequency at which the wavelength equals the circumference of the Earth, and higher harmonics occur at 14.1, 20.3, 26.4, and 32.4 Hz, etc. Lightning strikes excite these resonances, causing the Earth–ionosphere cavity to "ring" like a bell, resulting in a peak in the noise ...
Winfried Otto Schumann (May 20, 1888 – September 22, 1974) was a German physicist and electrical engineer who predicted the Schumann resonances, a series of low-frequency resonances caused by lightning discharges in the atmosphere.
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where E z is the vertical component of the electric field at the receiver in a distance ρ from the transmitter, E o is the electric field of a Hertzian dipole in free space, and = the angular frequency. In free space, it is =. Evidently, the Earth–ionosphere waveguide is dispersive because the transfer function depends on frequency.
Resonance effect in electrical machines [ edit ] In radial flux rotating electric machines, resonance due to electromagnetic forces is particular as it occurs at two conditions: there must be a match between the exciting Maxwell force and the stator or rotor natural frequency, and between the stator or rotor modal shape and the exciting Maxwell ...
Sympathetic resonance or sympathetic vibration is a harmonic phenomenon wherein a passive string or vibratory body responds to external vibrations to which it has a harmonic likeness. [1] The classic example is demonstrated with two similarly-tuned tuning forks .