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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.
Up to 99.63 °C (the boiling point of water at 0.1 MPa), at this pressure water exists as a liquid. Above that, it exists as water vapor. Note that the boiling point of 100.0 °C is at a pressure of 0.101325 MPa (1 atm ), which is the average atmospheric pressure.
Water has a very high specific heat capacity of 4184 J/(kg·K) at 20 °C (4182 J/(kg·K) at 25 °C) —the second-highest among all the heteroatomic species (after ammonia), as well as a high heat of vaporization (40.65 kJ/mol or 2268 kJ/kg at the normal boiling point), both of which are a result of the extensive hydrogen bonding between its ...
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.
3.4: Polypropylene: 2.2–2.36 Polystyrene: 2.4–2.7 Carbon disulfide: 2.6: BoPET: 3.1 [2] Paper, printing: 1.4 [3] (200 kHz) Electroactive polymers: 2–12 Mica: 3–6 [2] Silicon dioxide: 3.9 [4] Sapphire: 8.9–11.1 (anisotropic) [5] Concrete: 4.5: Pyrex : 4.7 (3.7–10) Neoprene: 6.7 [2] Natural rubber: 7: Diamond: 5.5–10 Salt: 3–15 ...
High dielectric constant. Flammable. Refined and dried castor oil is used in some high voltage capacitors. Hatcol 5005 synthetic ester [2] 3.2: High dielectric constant. Fire Resistant. Biodegradable PCB replacement. Low temperature fluidity. Silicone oil: 2.3–2.8 (-20) [clarification needed] [3] 1.0-1.2 [1] More expensive than hydrocarbons ...
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 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.