Relative Permittivity and Dielectric Constant

The relative permittivity, denoted f , is a dimensionless physical quantity equal to the ratio of the permittivity of the medium to the permittivity of a vacuum. It is also called the dielectric constant of the medium. Hence, it is defined by the equation e = e -e,. 

Moreover, the relative permittivity of an insulating material depends on the frequency, v, in Hertz (Hz) of the applied electric field and can be described as a complex physical quantity, where the imaginary part is related to dielectric losses  

Usually dielectric constants of materials listed in tables and databases are measured at a frequency of 1 MHz unless otherwise specified. 

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