What is Permittivity ?

what is permittivity??In electromagnetism permittivity which called absolute permittivity  is denoted by the Greek latter Ꜫ ( Epsilon). Ꜫ describe the amount of charge needed to generate one unit of electric flux in given medium

The SI unit of Ꜫ is Farad/meter or F/m or F.m-1

Permittivity is the ability of material to store an electric field in the polarization of the medium.


The lowest Ꜫ which is the vaccum Ꜫ ,called the electric constant and is represented by Ꜫo and its value is approximately 8.85x 10-12 F.m-1

Ꜫ of dielectric medium is the ratio of its absolute permittivity to the electric constant .The dimensionless quantity is called the relative permittivity .Relative permittivity is referred to as the dielectric constant

Relative  permittivity  equation

A perfect vaccum has a relative permitivity of exactly 1.The difference between the Ꜫ of vaccum and air is offenly negligible as

air permitivity

Relative permitivity is related to electric susceptibility ( X ) which is a measure of how easily a dielectric polarizes in response to an electric field ,and is given by


Unit of Ꜫ

The SI unit of Ꜫ is farad per meter (F/m or F.m-1

SI Unit of permittivity

There is a lot of substances having  dielectric constant  er greater than 1. These are generally called dielectric materials or simply called dielectrics

Commonly used dielectrics are mica ,glass paper, various ceramics, polyethylene, and certain metal oxides. Dielectrics are used in capacitors and transmission lines in alternating current ( AC ) audio frequency (AF), and radio frequency ( RF )applications.

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