Question

What is the electric susceptibility of a dielectric material?

Answer 1

The electric susceptibility of a dielectric material is a measure of how easily the material becomes polarized when an electric field is applied to it. It describes the material's response to the electric field in terms of its ability to polarize, or how much the electric field causes the material's charges to shift and create a separation of positive and negative charges.

In simpler terms:

When you apply an electric field to a dielectric material (which is a non-conducting material), the electric charges within the material shift slightly, causing polarization. The electric susceptibility quantifies how much the material gets polarized for a given electric field.

Formula:

The electric susceptibility (\(\chi_e\)) is related to the material's polarization (\(\mathbf{P}\)) and the applied electric field (\(\mathbf{E}\)) by this equation:
\[
\mathbf{P} = \epsilon_0 \chi_e \mathbf{E}
\]
Where:

1. \(\mathbf{P}\) is the polarization (the dipole moment per unit volume),
   

1. \(\mathbf{E}\) is the applied electric field,
   

1. \(\epsilon_0\) is the permittivity of free space, and
   

1. \(\chi_e\) is the electric susceptibility.
   

Key Points:

1. Susceptibility and Polarization: The higher the susceptibility, the easier it is for the material to become polarized.
   

1. Relation to Permittivity: The electric susceptibility is related to the relative permittivity (\(\epsilon_r\)) of the material:
   

   \[
   \epsilon_r = 1 + \chi_e
   \]
   So, if the material has a high susceptibility, it will also have a high relative permittivity.

Example:

1. Vacuum: \(\chi_e = 0\), meaning it does not get polarized at all.
   

1. Water: A high electric susceptibility, meaning it polarizes easily under an electric field.
   

Electric susceptibility is an important property for understanding how materials behave in electric fields, which is crucial in designing capacitors, insulators, and other electrical components.