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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.
1.333 at 20 °C Dielectric constant [2] 88.00 at 0 °C 86.04 at 5 °C 84.11 at 10 °C ... Up to 99.63 °C (the boiling point of water at 0.1 MPa), at this pressure ...
At the zero-pressure limit, the compressibility reaches a minimum of 4.4 × 10 −10 Pa −1 around 45 °C before increasing again with increasing temperature. As the pressure is increased, the compressibility decreases, being 3.9 × 10 −10 Pa −1 at 0 °C and 100 megapascals (1,000 bar). [42] The bulk modulus of water is about 2.2 GPa. [43]
A table of some typical values can be found under dielectric constant. Water has a relatively high dielectric constant value of 78.7 at 298K (25 °C), so in aqueous solutions at ambient temperatures 1:1 electrolytes such as NaCl do not form ion pairs to an appreciable extent except when the solution is very concentrated.
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 ...
Polarizability is responsible for a material's dielectric constant and, at high (optical) frequencies, its refractive index. The polarizability of an atom or molecule is defined as the ratio of its induced dipole moment to the local electric field; in a crystalline solid, one considers the dipole moment per unit cell. [1]
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 ).
) and the concentration of hydroxide (OH −) are increased while the pH remains neutral. Specific heat capacity at constant pressure also increases with temperature, from 4.187 kJ/kg at 25 °C to 8.138 kJ/kg at 350 °C. A significant effect on the behaviour of water at high temperatures is decreased dielectric constant (relative permittivity). [2]