The dielectric characteristics of a material are determined by the dielectric constant or relative permittivity of the material.
It is defined as the ratio of the permittivity of the medium to the permittivity of the free space.
\varepsilon_{\mathrm{r}}=\frac{\varepsilon}{\varepsilon_0}where ε0 = 8.854 x 10-12 F/m and for a dielectric medium εr >> 1 .
The dielectric constant of a material is also equal to the ratio of the capacitance of a capacitor with and without the dielectric material.
The dielectric constant (εr) determines the extent at which more dipoles can be created within a dielectric material. If εr increases, more dipoles can be created, polarization is more and hence more energy can be stored.
Electric Susceptibility (χe)
The electric susceptibility (χe) of a dielectric material is a measure of how easily it polarizes in response to an electric field. This it determines the electric permittivity of the material and thus influences many other phenomena in that medium .
It is defined as the constant of proportionality relating an electric field E to the induced dielectric polarization density P such that
P = ε0 χe E
where ε0 is the electric permittivity of free space. by
The susceptibility of a medium is related to its relative permittivity εr by
χe = εr – 1
In the case of a vacuum, χe = 0
The electric displacement D is related to the polarization density P by,
D = ε0 E + P = ε0 ( 1+χe ) E = εr ε0 E
Relative between Electric Susceptibility (χ) and relative permittivity (εr )
We know that P ∞ E
\begin{aligned} & \mathrm{P}=\varepsilon_0 \chi_{\mathrm{e}} \mathrm{E} \\ & \chi_{\mathrm{e}}=\frac{\mathrm{P}}{\varepsilon_0 \mathrm{E}} \end{aligned}But εr = 1+ χe
χe = εr -1
∴ we can write P = ε0 E (εr -1 )
It is a measure of characteristics of every dielectric.
| Read More Topics |
| Electrical conductivity in intrinsic semiconductor |
| Charge densities in a semiconductor |
| Basic definitions of magnetic materials |
