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Relative Permittivity - the Dielectric Constant

Common materials and their relative permittivity.

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

εr = 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 - εr - and permittivity - ε - for some substances. Note that permittivity may change with temperature for most materials.

Relative Permittivity Constants
ProductRelative Permittivity
- εr -
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
Water1) 4 - 88
Wood, Dry 2 - 6

1) Water - permittivity is 88 at 0 oC (31 oF) and drops with rising temperature. Permittivity is 80 at 20 oC (211 oF) and 55.3 at 100 oC (211 oF).

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