In electromagnetism, permittivity is the measure of how much resistance is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. Permittivity is determined by the ability of a material to polarize in response to the field, and thereby reduce the total electric field inside the material. Thus, permittivity relates to a material's ability to transmit (or "permit") an electric field.
It is directly related to electric susceptibility, which is a measure of how easily a dielectric polarizes in response to an electric field.
In SI units, permittivity Îµ is measured in farads per meter (F/m); electric susceptibility Ï is dimensionless. They are related to each other through
where Îµr is the relative permittivity of the material, and Îµ0 = 8.85â¦ Ã 10â12 F/m is the vacuum permittivity.
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