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Relative permittivity
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Relative <a href="/facts/Permittivities/Sd3WtgT1">permittivities</a> of some materials at <a href="/facts/Room_temperature/YHwUIUTE">room temperature</a> under <a href="/facts/Radio_wave/XmB6WPpF">1 kHz</a><table><tbody><tr><th>Material</th><th>εr</th></tr><tr><td><a href="/facts/Vacuum/BTk3goyV">Vacuum</a></td><td>1 (by definition)</td></tr><tr><td><a href="/facts/Air/hQ95Jznz">Air</a></td><td>1.00058986±0.00000050 (at <a href="/facts/Standard_temperature_and_pressure/JhJv9KFJ">STP</a>, 900 kHz),</td></tr><tr><td><a href="/facts/PTFE/jesBNXKq">PTFE</a>/Teflon</td><td>2.1</td></tr><tr><td><a href="/facts/Polyethylene/LaaAf4cn">Polyethylene</a>/XLPE</td><td>2.25</td></tr><tr><td><a href="/facts/Polyimide/4nW9HVKF">Polyimide</a></td><td>3.4</td></tr><tr><td><a href="/facts/Polypropylene/HM9PvoCz">Polypropylene</a></td><td> 2.2–2.36</td></tr><tr><td><a href="/facts/Polystyrene/dfIVntty">Polystyrene</a></td><td> 2.4–2.7</td></tr><tr><td><a href="/facts/Carbon_disulfide/b04Tadmy">Carbon disulfide</a></td><td>2.6</td></tr><tr><td><a href="/facts/BoPET/Eg8XF4F0">BoPET</a></td><td>3.1</td></tr><tr><td><a href="/facts/Paper/FUETwwKV">Paper</a>, printing</td><td>1.4 (200 kHz)</td></tr><tr><td><a href="/facts/Electroactive_polymers/0Xb8oupM">Electroactive polymers</a></td><td> 2–12</td></tr><tr><td><a href="/facts/Mica/ag4cdnsb">Mica</a></td><td> 3–6</td></tr><tr><td><a href="/facts/Silicon_dioxide/A3WILp6J">Silicon dioxide</a></td><td>3.9</td></tr><tr><td><a href="/facts/Sapphire/C11GJAmm">Sapphire</a></td><td> 8.9–11.1 (anisotropic)</td></tr><tr><td><a href="/facts/Concrete/K6whGVNx">Concrete</a></td><td>4.5</td></tr><tr><td><a href="/facts/Pyrex/TsG4WXde">Pyrex</a> (<a href="/facts/Glass/hezRsAGf">glass</a>)</td><td>4.7 (3.7–10)</td></tr><tr><td><a href="/facts/Neoprene/MtLEdFvE">Neoprene</a></td><td>6.7</td></tr><tr><td><a href="/facts/Natural_rubber/CbsjJxhY">Natural rubber</a></td><td>7</td></tr><tr><td><a href="/facts/Diamond/IBUdnd1y">Diamond</a></td><td> 5.5–10</td></tr><tr><td><a href="/facts/Salt/SCplalQ3">Salt</a></td><td> 3–15</td></tr><tr><td><a href="/facts/Melamine_resin/njNDyuNx">Melamine resin</a></td><td> 7.2–8.4</td></tr><tr><td><a href="/facts/Graphite/sSf3KMXr">Graphite</a></td><td> 10–15</td></tr><tr><td><a href="/facts/Silicone_rubber/3XMpD7m9">Silicone rubber</a></td><td> 2.9–4</td></tr><tr><td><a href="/facts/Silicon/cgWx0hdr">Silicon</a></td><td>11.68</td></tr><tr><td><a href="/facts/GaAs/BakLFjpp">GaAs</a></td><td>12.4</td></tr><tr><td><a href="/facts/Silicon_nitride/58X9QPQJ">Silicon nitride</a></td><td> 7–8 (polycrystalline, 1 MHz)</td></tr><tr><td><a href="/facts/Ammonia/MtLtJFtz">Ammonia</a></td><td> 26, 22, 20, 17 (−80, −40, 0, +20 °C)</td></tr><tr><td><a href="/facts/Methanol/EIfpoNCg">Methanol</a></td><td>30</td></tr><tr><td><a href="/facts/Ethylene_glycol/stFz6CVe">Ethylene glycol</a></td><td>37</td></tr><tr><td><a href="/facts/Furfural/xnnVJtsQ">Furfural</a></td><td>42.0</td></tr><tr><td><a href="/facts/Glycerol/sRQ6NBQQ">Glycerol</a></td><td> 41.2, 47, 42.5 (0, 20, 25 °C)</td></tr><tr><td><a href="/facts/Water/0lkXnJPK">Water</a></td><td> 87.9, 80.2, 55.5(0, 20, 100 °C) for visible light: 1.77</td></tr><tr><td><a href="/facts/Hydrofluoric_acid/wdXqu4bE">Hydrofluoric acid</a></td><td> 175, 134, 111, 83.6 (−73, −42, −27, 0 °C),</td></tr><tr><td><a href="/facts/Hydrazine/G7P5ITzU">Hydrazine</a></td><td>52.0 (20 °C),</td></tr><tr><td><a href="/facts/Formamide/IP7mDEFF">Formamide</a></td><td>84.0 (20 °C)</td></tr><tr><td><a href="/facts/Sulfuric_acid/Wom6fymJ">Sulfuric acid</a></td><td> 84–100 (20–25 °C)</td></tr><tr><td><a href="/facts/Hydrogen_peroxide/vju6HBIc">Hydrogen peroxide</a></td><td> 128 <a href="/facts/Aqueous/eRNr3MH2">aqueous</a>–60(−30–25 °C)</td></tr><tr><td><a href="/facts/Hydrocyanic_acid/vNtA0Mxe">Hydrocyanic acid</a></td><td> 158.0–2.3 (0–21 °C)</td></tr><tr><td><a href="/facts/Titanium_dioxide/T0KWmKcz">Titanium dioxide</a></td><td> 86–173</td></tr><tr><td><a href="/facts/Strontium_titanate/fQ4lC197">Strontium titanate</a></td><td>310</td></tr><tr><td><a href="/facts/Barium_strontium_titanate/Gu39aNyo">Barium strontium titanate</a></td><td>500</td></tr><tr><td><a href="/facts/Barium_titanate/v0v8cEfC">Barium titanate</a></td><td> 1200–10,000 (20–120 °C)</td></tr><tr><td><a href="/facts/Lead_zirconate_titanate/oIaB8VgS">Lead zirconate titanate</a></td><td> 500–6000</td></tr><tr><td><a href="/facts/Conjugated_system/Ddx9qzox">Conjugated polymers</a></td><td> 1.8–6 up to 100,000</td></tr><tr><td><a href="/facts/Calcium_copper_titanate/Qpjz4GIg">Calcium copper titanate</a></td><td> >250,000</td></tr></tbody></table> <p>The relative permittivity (in older texts, dielectric constant) is the <a href="/facts/Permittivity/Sd3WtgT1">permittivity</a> of a material expressed as a ratio with the <a href="/facts/Vacuum_permittivity/gWRUhPGY">electric permittivity of a vacuum</a>. A <a href="/facts/Dielectric/PnVt9P2G">dielectric</a> 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. </p><p>Permittivity is a material's property that affects the <a href="/facts/Coulomb_force/V0lR5NKv">Coulomb force</a> between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum. </p><p>Likewise, relative permittivity is the ratio of the <a href="/facts/Capacitance/0pH046TL">capacitance</a> of a <a href="/facts/Capacitor/hyowqv7n">capacitor</a> using that material as a <a href="/facts/Dielectric/PnVt9P2G">dielectric</a>, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as the dielectric constant, a term still used but deprecated by standards organizations in engineering as well as in chemistry. </p>