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The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field.
Water is the most abundant substance on Earth's surface and also the third most abundant molecule in the universe, after H 2 and CO. [23] 0.23 ppm of the earth's mass is water and 97.39% of the global water volume of 1.38 × 10 9 km 3 is found in the oceans. [84]
A liquid dielectric is a dielectric material in liquid state. Its main purpose is to prevent or rapidly quench electric discharges . Dielectric liquids are used as electrical insulators in high voltage applications, e.g. transformers , capacitors , high voltage cables , and switchgear (namely high voltage switchgear ).
Another common term encountered for both absolute and relative permittivity is the dielectric constant which has been deprecated in physics and engineering [2] as well as in chemistry. [ 3 ] By definition, a perfect vacuum has a relative permittivity of exactly 1 whereas at standard temperature and pressure , air has a relative permittivity of ...
A dielectric resonator oscillator (DRO) is an electronic component that exhibits resonance of the polarisation response for a narrow range of frequencies, generally in the microwave band. It consists of a "puck" of ceramic that has a large dielectric constant and a low dissipation factor. Such resonators are often used to provide a frequency ...
The dielectric constant of water decreases with increasing temperature to about 55 at 100 °C and about 5 at the critical temperature (217.7 °C). [15] Thus ion pairing will become more significant in superheated water. Solvents with a dielectric constant in the range, roughly, 20–40, show extensive ion-pair formation.
Dielectric constant [2] 88.00 at 0 °C 86.04 at 5 °C 84.11 at 10 °C 82.22 at 15 °C 80.36 at 20 °C 78.54 at 25 °C 76.75 at 30 °C ... Over liquid water.
These characteristics, along with the high dielectric constant, make water an excellent choice for building large capacitors. The drawback to using water is the short length of time it can hold off the voltage, typically in the microsecond to ten microsecond (μs) range. Deionised water is relatively inexpensive and is environmentally safe.