We developed a digital technique for determination of dielectric constant of non conducting liquid. But while adopting such technique for determination of dielectric constant of water we face difficulty. Hence I am looking for a simple technique for determination of dielectric constant of liquids both a non conducting and slightly conducting one.
For simple water models, I used the Structure Factor, which is calculated as sum of two terms: Intra- and Intermolecular parts. \eps(k) = 1/(1-4pi \beta S(k)), where S(k) is the structure factor in k-space. This is calculated using molecular dynamics simulations and radial distribution functions; of course static dielectric constant will be defined as lim when k->0, which means large box size, but with molecular dynamics techniques available, systems with these box sizes can be computationally efficient.
There is literature around for this technique.
Kind attention to Dr. Kamberaj: The answer as mentioned by you is a theoretical treatment only. I am looking for a simple experimental approach to determine dielectric constant of different types of liquids. Hence answer in that direction is requested.
For an accurate measurement, hook up a network analyzer to both ends of a tube filled with the sample. The ratio of reflected vs. transmitted power is related to the dielectric constant. Note that dielectric constants are usually wavelength dependent.
www3.imperial.ac.uk/pls/portallive/docs/1/11949698.PDF
An easier simple method is to connect a tube between two parallel capacitors filled with varying amounts of your liquid. This is very simple in theory but may be difficult to get to work.
A third method is to use a cylindrical capacitor immersed in the liquid. When the capacitor is turned on, the liquid will rise to an amount determined by the dielectric susceptibility
www.df.unipi.it/~macchi/FISICA2/PROBLEMS/dielecliquid.pdf
You can use a cylindrical capacitor as Jeff suggests but instead of measuring the height of the liquid you can put the capacitor as one arm of an AC Wheatstone bridge and measure the capacitance with and without the fluid; the ratio is the dielectric constant. Because the dielectric constant is function of frequency and temperature, you may need to control the temperature and measure at different frequencies depending on your application and the necessary precision. A capacitance cell design appears in an article we wrote in Reviews of Scientific Instruments, Volume 51, p. 994 (1980)
Kind attention to Dr. Brender and Dr. Jacobs. Thank you for your suggestions. I shall try accordingly to solve my problem.
A cylindrical capacitor and a bridge can be used. See our paper for such a setup:
https://www.researchgate.net/publication/38014625_High-temperature_liquid_chromatography._Part_III_Determination_of_the_static_permittivities_of_pure_solvents_and_binary_solvent_mixtures--implications_for_liquid_chromatographic_separations?ev=prf_pub
Regards
Peter
Article High-temperature liquid chromatography. Part III: Determinat...
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