Dielectric Properties

What is Dielectric Material?

A dielectric material is defined as the non-metallic material with specific resistance high, temperature coefficient of resistance negative and with large insulation resistance. The other way of defining dielectric material is that it is non-conducting material which stores electrical charges.

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

Above figure explains the polarisation of dielectric molecules when the electric field is applied.

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

Properties of Dielectric Material

Following are the exhibited by the dielectric materials:

  • The energy gap in the dielectric materials is very large.
  • The temperature coefficient of resistance is negative and the insulation resistance is high.
  • The dielectric materials have high resistivity.
  • The attraction between the electrons and the parent nucleus is very strong.
  • The electrical conductivity of these materials is very low as there are no free electrons to carry current.

What are Dielectric Properties?

Dielectric properties of materials are defined as a molecular property which is fundamental in all the materials that are capable of impending electron movement resulting in polarization within the material on exposure to an external electric field.

What are Dielectric Properties of Insulation?

Following are the dielectric properties of insulation:

  • Breakdown voltage
  • Dielectric parameters such as:
    • Conductivity 
    • Power factor
    • Loss angle
    • Permittivity 

What are Dielectric Properties of Solids?

Following are the dielectric properties of solids:

  • Piezoelectricity 
  • Pyroelectricity 
  • Ferroelectricity 
  • Anti ferroelectricity

What are Dielectric Properties of Food?

Following are the dielectric properties that influence the food:

  • Frequency of microwave or the radio frequencies
  • Amount of water present in food
  • Temperature 
  • The density of the material
  • Composition and structure of the material

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

  • Dielectrics are used as a capacitor for storing energy.
  • The dielectric material in a transformer is used as an insulator and as a cooling agent.

Physics-related topics:

 

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