Water capacitor

Water capacitors were created mainly as a novelty item or for laboratory experimentation and can be made with simple materials.

These characteristics, along with the high dielectric constant, make water an excellent choice for building large capacitors.

Thus, in certain unusual situations, such as the generation of extremely high voltage but very short pulses, a water capacitor may be a practical solution – such as in an experimental X-ray pulser.

[6] The observed discharge trend could be described by a Modified Poisson-Boltzmann Equation only when the voltage was very low and the system capacitance showed a dependence on the spacing between the two platinum plates.

Once the same capacitor was partially submerged in deionised water (DI), or DI with low dissolved NaCl concentrations, still with only ambient air between the electrodes, the capacitance, energy density, and power density, at low frequency, increased by more than seven orders of magnitude.

Notably, conventional theory precludes the possibility that material outside the volume between the plates will in any fashion impact capacitive behavior.

This movement resulted in the formation of an ion double-layer with a steeply rising electric field and a maximum pH of approximately 12.

There is an opinion that a Helmholtz double layer is not responsible for the observed electrokinetic phenomena and that the classical formulae are not strictly applicable when there exists unbalanced dissolved charges at interfaces.

With deionised water between the tubes, the magnitude and phase of the interior electric field was measured from 100 Hz to 300 kHz.

The high-pass filter frequency response expected for a dielectric tube with non-negligible conductivity was observed.

The model also predicted that at zero frequency (a static electric field) pure water would be expected to behave as a Faraday cage.

Water capacitors, being self-discharging, (for totally pure water, only thermally ionized, at 25 °C (77 °F) the ratio of conductivity to permittivity means that self-discharge time is circa 180μs, faster with higher temperatures or dissolved impurities) usually cannot be made to store enough residual electrical energy to cause serious bodily injury.

[13] Capacitors can originally be traced back to a device called a Leyden jar, created by the Dutch physicist Pieter van Musschenbroek.

A rod electrode was directly connected to the inlayer of foil by means of a small chain or wire.