Relative Permittivity - the Dielectric Constant
The dielectric constant - also called the relative permittivity indicates how easily a material can become polarized by imposition of an electric field on an insulator. Relative permittivity is the ratio of "the permittivity of a substance to the permittivity of space or vacuum ".
Relative permittivity can be expressed as
ε r = ε / ε0 (1)
where
εr = relative permittivity - or dielectric constant
ε = permittivity of substance (C2/(N m2))
ε0 = permittivity of vacuum or free space (8.854187817 10-12 C2 /(N m2 ))
Relative permittivity - ε r - and permittivity - ε - for some substances. Note that permittivity may change with temperature for most materials.
| Product | Relative Permittivity - ε r - 10-12 |
|---|---|
| Acetaldehyde (41°F) | 21.8 |
| Acetic Acid (68°F) | 6.2 |
| Acetic Acid (36°F) | 4.1 |
| Acetone (77°F) | 20.7 |
| Acetone (127°F) | 17.7 |
| Acetone (32°F) | 1.0159 |
| Acetyl Acetone (68°F) | 23.1 |
| Acetyl Bromide (68°F) | 16.5 |
| Acetyl Chloride (68°F) | 15.8 |
| Acetyle Acetone (68°F) | 25.0 |
| Acetylene (32°F) | 1.0217 |
| Air (Dry) (68°F) | 1.000536 |
| Air, Liquid (-191 oC) | 1.4 |
| Alcohol, Industrial | 16-31 |
| Alumina | 9.3-11.5 |
| Aluminum Bromide (212°F) | 3.4 |
| Aluminum Fluoride | 2.2 |
| Amber | 2.8-2.9 |
| Ammonia (-74°F) | 25 |
| Ammonia (-30°F) | 22.0 |
| Ammonia (40°F) | 18.9 |
| Ammonia (69°F) | 16.5 |
| Aniline (32°F) | 7.8 |
| Aniline (68°F) | 7.3 |
| Aniline (212°F) | 5.5 |
| Araldite | 3.6 |
| Argon (68°F) | 1.000513 |
| Bakelite | 3.5-5.0 |
| Bakelite, mica filled | 4.7 |
| Benzene (68°F) | 2.3 |
| Body tissue | 8 |
| Butane (30°F) | 1.4 |
| Carbon dioxide (68°F) | 1.000921 |
| Carbon disulfide | 2.6 |
| Calcium | 3.0 |
| Casting compound | 2.5 |
| Caster oil | 4.7 |
| Cellulose acetat | 3.3 - 3.9 |
| Ceramic, MgNb2O6 | 21 |
| Ceramic, ZnNb2O6 | 25 |
| Ceramic, MgTa2O6 | 28 |
| Ceramic, ZnTa2O6 | 38 |
| Chlorine (32°F) | 2.0 |
| Chloroform (68°F) | 4.8 |
| Concrete | 4.5 |
| Diamond | 5.5 - 10 |
| Ebonite | 2.5 - 2.9 |
| Epoxy Resin (Cast ) | 3.6 |
| Ethanol (25 oC, 77°F) | 24.3 |
| Ethyl Acetate (77°F) | 6.0 |
| Ethyl Alcohol (77°F) | 24.3 |
| Ethylene glycol | 37 |
| Formamide (20 oC) | 84 |
| Formica | 4.6 - 4.9 |
| Furfural | 42 |
| R12 Dichlorodifluoromethane (70°F) | 2.4 |
| Glass | 3.7 - 10 |
| Glass, Pyrex | 4.8 |
| Glycerin, Liquid | 47-68 |
| Glycerol (77°F) | 42.5 |
| Granite | 7 - 9 |
| Graphite | 10 - 15 |
| Guttapercha | 4 |
| Hard paper, laminated | 4.5 |
| Hydrazine (20 oC) | 52 |
| Hydrocyanic acid (21 oC) | 2.3 |
| Hydrofluoric acid (0 oC) | 83.6 |
| Hydrogen peroxide (25 oC) | 60 |
| Ice (-2 oC) | 3.2 |
| Isoprene (77°F) | 2.1 |
| Insulation of high voltage cables | 4.2 |
| Insulation of telephone cables | 1.5 |
| Marble | 8 |
| Methanol (20 oC)) | 33.6 |
| Mica | 2.5 - 7 |
| Mineral Oil (80°F) | 2.1 |
| Mylar | 3.1 |
| Neoprene | 6.7 |
| Nitrogen (68°F) | 1.000580 |
| Nylon | 4.0 - 5.0 |
| Oil paper | 4 |
| Olive oil | 3 |
| Paper | 2.3 |
| Paper, impregnated | 5 |
| Paper, waxed | 2.5 |
| Paraffin oil | 2.2 |
| Paraffin Wax | 2.1-2.5 |
| Petroleum | 2.2 |
| Phenolic resin | 8 |
| Plexiglass | 3.2 |
| Polyester Resin | 2.8 - 4.5 |
| Polyethylene, XLPE | 2.2-2.4 |
| Polyamide | 2.8 |
| Polymide | 3.4 |
| Polypropylene | 2.2 |
| Polystyrene | 3 |
| Porcelain | 5.0-7.0 |
| Pressed board | 4 |
| Pyrex Glass | 4.3 - 5.0 |
| Quartz | 4.5 |
| Rubber | 3.0 |
| Salt | 3.0 - 15.0 |
| Sapphire | 8.9 - 11.1 |
| Shellac | 3.5 |
| Silica Sand | 2.5-3.5 |
| Silicon | 11.0 - 12.0 |
| Silicon dioxide | 3.9 |
| Silicon oil | 2.2 - 2.8 |
| Slate | 4 |
| Sodium chloride | 5.6 |
| Soft rubber | 2.5 |
| Steatite | 6 |
| Sulfur | 3.5 |
| Sulfuric acid (20 oC) | 84 |
| Polytetrafluoroethylene (PTFE) | 2 |
| Teflon, PTFE | 2.1 |
| Titanium dioxide | 86 - 173 |
| Transformer oil, mineral | 2.2 |
| Transformer oil, vegetable | 2.5 |
| Turpentine | 2.2 |
| Vacuum | 1 |
| Vulcanized fibres | 2.5 |
| Water 1) | 4 - 88 |
| Wood, Dry | 2 - 6 |
1) Water - permittivity is 88 at 0 oC (32 oF) and drops with rising temperature. Permittivity is 80 at 20 oC (212 oF) and 55.3 at 100 oC (212 oF).
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