P19-150 – Application: dielectric materials

Application: dielectric materials

Dielectric materials – also known as insulating materials – contain polar molecules with dipole moments that are generally oriented in random directions.

These molecules are not free to flow through the dielectric material, but they can rotate and orient themselves under the effect of an applied electric field. Once they rotate and align their dipole moments with the external electric field, the material will be polarized as shown below.

The net effect of orienting the dipole moments along the external electric field is to decrease the net electric field within the material since the individual electric field of each dipole points opposite the direction of the applied electric field and contributes to decreasing the net electric field.

Dielectric materials are characterized by a dielectric constant $\kappa >1$ that represents by what factor the dielectric material is a better insulator than vacuum. Indeed, the permittivity of a dielectric material is related to the permittivity of free space ${\varepsilon }_0$ through the formula

\boxed{{\varepsilon }_d=\kappa {\varepsilon }_0}

A dielectric material with dielectric constant $\kappa $ is therefore $\kappa $ times better at insulating than vacuum or air.