Dielectric Properties - Terminology, Mechanism, Applications.

The word dielectric derived from dia+electric synonymous to zero electrical conductivity. thus exhibiting only displacement current making it ideal to store and return electrical energy.

Dielectric Properties mainly concerned with dissipation and storage of magnetic and electric energy in the material. A dielectric is an electric insulator but with the application of an electric field, they can be polarised. When a conductor placed in an electric field, the electric charges flow through the material. But it is not the same with dielectrics.

When a dielectric is placed in an electric field, the electric charges do not flow through the material, instead, they cause dielectric polarisation by shifting from the mean/equilibrium position. As a result, the positive charges are oriented in the same direction as that of the electric field and negative charges are shifted in the opposite direction. This phenomenon yields an internal electric field, which in turn reduces the overall electric field within the dielectric material.

Dielectric Properties

Figure(a) Polarisation of dielectric molecules when the electric field is applied.

The dielectrics are mostly solids. Some of the dielectrics are composed of weekly bonded molecules. In such scenarios along with polarisation, we can also observe that molecule reorient themselves as to align their symmetry axes with the field.

Difference between Dielectric and Insulators

Dielectrics are often confused with insulators. The insulator typically implies low electrical conductivity. However, the term dielectric typically used to denote the material with superior polarisability. It is expressed numerically using relative permittivity. Insulator indicates the electrical obstruction whereas the dielectric indicate the ability of a material to store energy(by the means of polarisation). The common example is a capacitor. Here a dielectric insulating plate is sandwiched between metallic plates. For a given electric field strength, the capacitor’s surface charge is raised by polarising the dielectric plate. Let us learn more differences between dielectric and insulators in the table given below:

Dielectric vs Insulators

Dielectrics

Insulators

Material that can develop an electric field with minimal loss of energy is known as a dielectric.

A substance that has low conductivity and that which obstructs the flow of current is known as an insulator.

Weakly bonded as compared to the insulators

Covalently bonded

Stores charges

Obstructs charges

Their application lies in power cables, capacitors and more

They are used in the high voltage system and conducting wires

Application of Dielectric Properties

These material act as a dam for electric energy because they can temporarily store electric charge. When a voltage difference is applied across dielectric material, electric polarisation is achieved which in turn helps to store electric energy for a short duration of time making it ideal to build a capacitor. This is an important mechanism which involves a wide range of applications in sub-disciplines of applied science such as:

  • Optics
  • Electronics
  • Cell biology
  • Solid state physics

Physics related topics:

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