What is a dielectric and what are the types of dielectric materials

What is a dielectric

Dielectric is a material which has poor electrical conductivity, so it can be considered as an insulator. These materials are used to prevent the flow of electricity through them so they can act as insulators, these materials can also be used to store electric charge or to increase the capacitance and they are termed as dielectrics. In dielectrics, the electrons are tightly bound to the nucleus so there won’t be any free electrons for conduction. Dielectrics have few electrons for electrical conductivity and hence it has a dipole. Dielectrics are used for two main purposes in electrical equipment they are insulation and electrical energy storage. Dielectric will be polarized by applying an electric field and dielectric materials do the charge storage by the polarization of the molecules.

What is the use of dielectric

Dielectrics can be used storing charge they can do this by the charge polarization of the molecules. Dielectric materials can increase the charge storage ability of a capacitor, it can do noise filtering from signals as a part of a resonance circuit, it can also supply power to another component. The ultralow dielectric constant is used for high-frequency switching applications, dielectric loss is used to heat food in a microwave oven.

Can a dielectric conduct electricity

Dielectric is an insulator so it can’t conduct electricity, they are mostly used as an insulating material. Dielectric acts as an insulator because the electrons in dielectrics are tightly bonded to the nucleus so there are no free electrons for conduction.

What is a dielectric-polarization

If an electric field is applied to a dielectric material, the negative and positively charged particles are separated in opposite directions and produce electric dipole within the material and this is called dielectric-polarization.

How a dielectric is different from an insulator

Dielectric materials and insulators have the same property both of then don’t conduct electricity. In insulators, there are no free electrons so there won’t be any electrical conduction but in case of dielectrics there are few electrons for electrical conductivity and it has a dipole. Dielectric materials can be used for insulation and electrical energy storage.

What is the purpose of a dielectric 

The main purpose of a dielectric is to control the flow of current between the conductors or between a conductor. Dielectrics are used as insulators in circuit breakers as gaseous insulation, oil insulation in a power transformer and polymer composite for insulator core. Dielectrics are used for storing electric charge.

What is dielectric strength

It is one of the most important properties of a dielectric, dielectric strength can be defined as the capacity of the material to withstand an electric field without breaking down and allows an electric current to pass. It is the measure of the resistance of the material to breakdown. In the case of dielectric breakdown a large discharge current passes through it. The factors that affect the dielectric strength in solids are molecular structure, impurities, temperature, and frequency. Dielectric strength decreases with an increase in temperature, humidity, and age of the material.

Dielectric strength= Breakdown voltage/ thickness of dielectric material

What is a dielectric loss

Dielectric loss is the measure of energy dissipated in a dielectric in unit time when an electric field acts on it. It is the lost electrical energy as heat during the polarization process. When the dielectrics are placed in an external AC field, their dipole will align in the different opposite directions and restores their original position. So the electrical energy will be absorbed by the material and dissipate in the form of heat. The dielectric loss increase when the frequency of the alternating voltage increases. Dielectric loss results from several mechanisms like ion migration, ion vibration, and deformation and electronic polarization.

What is dielectric break-down

If the dielectric materials are subjected to a high electric field, electrons could be torn from their atoms and it will give rise to a current through the insulator and this process is called the dielectric breakdown and the insulation property of the dielectric material is destroyed. Dielectric materials can resist the electric current flow and they can store electrical energy. The maximum voltage a dielectric material can withstand is known as the dielectric strength and if the applied electric field is higher than this then the dielectric breakdown takes place.

What is a dielectric constant

The dielectric constant can be described as the ratio of the permittivity of the medium to the permittivity of the free space. Permittivity is the quality that describes the effect of a material on an electric field, the higher the permittivity the more the material tends to reduce any field set up in it. Materials with high dielectric constant have a strong ability to become polarized. If the polarization developed by applying an electric field is high for a dielectric material then its dielectric constant will be high too. If resistance to the flow of electric current is high then the dielectric constant is also high.

What are the types of dielectric materials

Solid dielectrics

Dielectric materials are mostly solids, some of them are mica, glass, and plastics. Solid dielectric materials are used in capacitors some of them are mica, ceramics, and barium titanate. Quartz crystal is used to prepare an ultrasonic transducer.

Gaseous dielectrics

Dielectric gas can be used as an electric material it can be used to prevent rapidly quench electric discharge. Dielectric gases like air, nitrogen, hydrogen, and sulfur-hexafluoride are used in electrical insulators in high voltage applications like air-capacitors, transformers, circuit breakers, and switchgear.

Liquid dielectrics

A liquid dielectric is an insulating dielectric material in a liquid state and they are used to prevent quick electrical discharges. Dielectric liquids are used as electrical insulators in high voltage applications such as transformers, capacitors, and high voltage cables, and switch gears. Dielectric liquids can be used to provide electrical insulation, suppress corona and arcing, and to serve as a coolant.

What are the applications of dielectrics

  • The dielectric constant is useful in material processing, electronics, and biomedical engineering
  • Dielectrics are used in capacitors, it will be useful to store electric charge
  • It can filter out noise from signals as a part of the resonant circuit
  • The ultralow dielectric constant is useful for high electric frequency switching applications
  • Dielectric losses can be used to heat food in a microwave oven
  • Dielectric constant can be used to fabricate electronic equipment such as rectifiers, semiconductors, and transistors


post-graduate in Electronics & communication.

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