The frequency response curve of a series resonance circuit shows that the magnitude of the current is a function of frequency and plotting this onto a graph shows us that the response starts at near to zero, reaches maximum value at the resonance frequency when I MAX = I R and then drops again to nearly zero as ƒ becomes infinite. Resonance: Resonance is a phenomenon in which a dynamic force drives a structure to vibrate at its natural frequency. When a structure is in resonance, a small force can produce a large vibration response.
Patients with skin penetrating titanium implants in the temporal bone, for attachment of bone-anchored hearing aids, have made it possible to investigate the free-damped natural frequencies (resonance frequencies) of the human skull in vivo. The resonance frequencies of the skull of six subjects were investigated. Teh resonance frequencies were extracted from two frequency response functions (acceleration/force) measured on each subject: One point measurement where the force and acceleration were both measured at the same point, and one transcranial measurement where the acceleration was measured contralaterally. Between 14 and 19 resonance frequencies were identified for each subject in the frequency range 500 Hz to 7.5 kHz. The two lowest resonance frequencies were found to be on the average 972 (range 828-1164) and 1230 (range 981-1417) Hz.
The relative damping coefficients of all resonances were found to be between 2.6 and 8.9%. Due to the relatively high damping coefficients, it is assumed that the resonance frequencies do not significantly affect bone conducted sound. In the transcranial measurements, however, a few large antiresonances were found which may affect bone-conducted sound. Intersubject variations were large, probably due to individual variations in skull geometry and in mechanical parameters. The results were shown to be consistent with previous results obtained on dry skulls. No obvious correlation between lowest resonance frequency and skull size was found.
It depends on what you mean by resonate.Water has three different vibrational modes - there are vibrational frequencies associated with these, but these are not really oscillations like a mass on a spring which we would be familiar with seeing. The webpage you link has some 'vibrational frequencies' of different molcules and notes they are significantly higher than the 2.45 GHz microwave range.So water can be excited rotationally by 2.45 GHz - the rotational behaviour of water as single molecules in the gas phase is very complicated. Water is an 'asymmetric rotor', which turns out to be the hardest to understand. In liquid water the rotation is further complicated by collisions between adjacent molecules.2.45 GHz is used is because it is a standard frequency that is allowed and doesn't interfere with licensed communications systems, part of the 2.4 GHz.
A lot of questions and answers here raise more ambiguity without addressing the fundamental underlying principle of the microwave-water interaction. A microwave heats (imparts kinetic energy) to water not through resonance (that would be an absurd preposition given water has ridiculously high mechanical resonance frequency) but rather from dipole interaction.Water being a polar molecule gets activated by effect of its dipole moment (of about 2d) in a microwave field. The resulting molecules spin, being translated rotationally.To answer your question: no, it doesn't make sense talking about a resonant frequency of water at the molecular level. At those levels, sound or other forms of classical excitation cannot achieve sustained resonance given the vast normal modes and DOF of liquid molecules.
What is important in the idea of resonance with water is to establish a frequency of excitation that causes the natural frequencies to superimpose or wave superposition. By achieving wave superposition the amplitude of the oscillations will have the greatest potential of breaking the molecule into its elemental constituents thereby creating free atoms that can recombine to form the diatomic molecules desired. H2 and O2 Oddly enough chemistry and properties of elements can play into this process as the electrodes used if they are constructed of platinum will result in a better yield from hydrolysis. This may be the result of how the atomic structure of platinum releases electrons through solution.
A similar process has been observed in certain solar cells as alloys of atoms are placed on layers of silicon substrate creating a resonant cavity to enhance voltage production through the capture of photons. The explanation comes from the energy level of exchange of electrons during enthalpy processes that exceed the enthalpy energy required to break the covalent bonds of H2O.