Dielectric vs. Insulator

What's the Difference?

Dielectric and insulator are two terms used in the field of physics to describe materials that do not conduct electricity. However, there is a subtle difference between the two. An insulator is a material that does not allow the flow of electric current due to its high resistance. It completely blocks the movement of electrons and prevents the transfer of charge. On the other hand, a dielectric is a material that can store electrical energy in the form of an electric field. It can be polarized when subjected to an electric field, allowing the separation of positive and negative charges. While both dielectrics and insulators do not conduct electricity, dielectrics have the ability to store and release electrical energy, making them useful in capacitors and other electronic devices.


DefinitionA material that can store electrical energy in an electric field.A material that does not easily conduct electricity.
ExamplesPlastic, glass, ceramicRubber, wood, air
Electrical ConductivityLowVery low
Breakdown VoltageHigherLower
Dielectric ConstantGreater than 11
PolarizationCan be polarizedCannot be polarized
ApplicationsCapacitors, insulating materialsInsulation, electrical safety

Further Detail


When it comes to understanding the behavior of electricity and the role of materials in electrical systems, two terms that often come up are dielectric and insulator. While both dielectrics and insulators are used to prevent the flow of electric current, they have distinct attributes that set them apart. In this article, we will explore the characteristics of dielectrics and insulators, their applications, and how they differ from each other.

Definition and Function

A dielectric is a material that can store electrical energy in an electric field. It is commonly used in capacitors, where it separates the conductive plates and prevents direct contact between them. Dielectrics are chosen based on their ability to store charge and their breakdown voltage, which determines the maximum electric field they can withstand before losing their insulating properties.

On the other hand, an insulator is a material that resists the flow of electric current. It is used to isolate conductive elements and prevent electrical leakage. Insulators are typically chosen for their high resistivity, which inhibits the movement of electrons through the material. They are commonly employed in electrical wiring, power transmission lines, and various electrical devices.

Electrical Conductivity

One of the key differences between dielectrics and insulators lies in their electrical conductivity. Dielectrics are non-conductive materials, meaning they do not allow the flow of electric current under normal conditions. However, when subjected to an electric field, dielectrics become polarized, aligning their internal charges and allowing the storage of electrical energy. This property makes dielectrics useful in energy storage applications such as capacitors.

On the other hand, insulators have extremely low electrical conductivity. They are designed to prevent the flow of electric current and maintain electrical insulation between conductive elements. Insulators achieve this by having a high resistivity, which restricts the movement of electrons. This property ensures the safety and efficiency of electrical systems by minimizing the risk of electrical shocks and short circuits.

Dielectric Strength and Breakdown Voltage

Dielectric strength and breakdown voltage are important parameters that differentiate dielectrics from insulators. Dielectric strength refers to the maximum electric field a dielectric material can withstand without experiencing electrical breakdown. It is a measure of the material's ability to resist the flow of current under high voltage conditions. Dielectrics with higher dielectric strength can handle larger electric fields, making them suitable for high-voltage applications.

Insulators, on the other hand, also possess a breakdown voltage, but it is typically much higher than that of dielectrics. This is because insulators are designed to withstand higher voltages and provide a higher level of electrical insulation. The breakdown voltage of an insulator is determined by its resistivity and thickness. Insulators with higher resistivity and greater thickness can withstand higher voltages, making them essential for applications involving high-power transmission and distribution.


Dielectrics find numerous applications in electrical and electronic systems. They are commonly used in capacitors, where they store electrical energy and help regulate voltage levels. Dielectrics are also employed in insulating materials for cables and wires, preventing electrical leakage and ensuring efficient power transmission. Additionally, dielectrics are utilized in electronic components such as printed circuit boards (PCBs) and integrated circuits (ICs) to provide electrical insulation and protection against short circuits.

Insulators, on the other hand, have a wide range of applications in various industries. They are extensively used in power transmission and distribution systems to insulate overhead lines, underground cables, and transformers. Insulators also play a crucial role in electrical equipment such as switches, circuit breakers, and insulating bushings. Furthermore, insulators find applications in the construction industry for thermal insulation, soundproofing, and fire resistance.

Material Properties

Dielectrics and insulators can be made from a variety of materials, each with its own unique properties. Dielectrics are often made from materials such as ceramics, glass, plastics, and certain types of rubber. These materials possess high dielectric constants, allowing them to store significant amounts of electrical energy. Dielectrics can also be engineered to have specific properties, such as low dielectric loss, high thermal stability, and resistance to environmental factors.

Insulators, on the other hand, are typically made from materials with high resistivity, such as porcelain, glass, rubber, and various polymers. These materials exhibit low electrical conductivity and are chosen for their ability to withstand high voltages without breaking down. Insulators can also be designed to have additional properties, including mechanical strength, resistance to weathering, and resistance to chemical corrosion.


In summary, dielectrics and insulators are both essential components in electrical systems, but they serve different purposes and possess distinct attributes. Dielectrics are non-conductive materials that can store electrical energy in an electric field, making them suitable for energy storage applications. Insulators, on the other hand, are materials with high resistivity that prevent the flow of electric current, ensuring electrical insulation and safety in various applications.

Understanding the differences between dielectrics and insulators is crucial for engineers and technicians working in the field of electrical engineering. By selecting the appropriate material for a specific application, they can ensure the efficient and safe operation of electrical systems, whether it be in power transmission, electronic devices, or other electrical equipment.

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