Dielectric Meaning

Dielectric is a material that possesses insulating properties. It is a substance that has the ability to transmit electric force without conduction.

We see many kinds of electric and polarized materials that have some sort of combined property. As you go through this article, you will come across many terms related to dielectric and its applications in today’s life situations. You will also get to know unitless values and numbers that describe the behaviour of electric insulators when kept under the influence of an electric field. So, let’s hop-down!


What is Dielectric?

In the above text, we understood how to define dielectric, i.e., a dielectric aka dielectric material is an electrical insulator. When it is subjected to the external electric field, it gets polarized. Also, they are very poor conductors of electricity.

Now, what is dielectric material? A dielectric particle is an insulator. 

So, what is the dielectric definition?


Point to Note:

Electric charges don’t flow through the materials as they react when subjected to an electrical conductor; however, they shift from their position and value that leads to dielectric polarization. Since the material is polarized, the positive charges get displaced towards the field, and negative charges go away from the field. 

For instance, if the field moves in the x-axis, the negative charges get directed towards the negative x-axis. This, in turn, builds an internal electric field that minimizes the overall area inside the dielectric. In case the dielectric has weak bond molecules, they will not only get polarized but also become re-oriented letting the symmetric axes to be aligned with respect to the field.


Define Dielectric Constant

The dielectric constant is the ratio of Permittivity of a substance to the Permittivity of free space. Further, it is expressed as the extent to while any element gets intensified by the electric flux. This becomes the electrical equivalent of relative magnetic permeability. 


Concept of Dielectric Constant 

With the rise of the dielectric constant, there is also a sharp rise in electric flux density. However, the remaining factors don’t change. This lets the element of any material size like metal plates maintain the electric charge for a lengthy time-span, thereby holding a considerable amount of charge. Besides, substances that possess high dielectric constants are applied to be used in creating highly valued capacitors.

You cannot desire any high dielectric constant through its own properties. Honestly speaking, these substances will break down more naturally when it is under the subjection of a high electric field. This is unlike the case with materials having a low dielectric constant. 

For instance, dry air possesses a low dielectric constant; however, this is the best example of dielectric materials for capacitors. As such, it has considerably been used in high power radio frequency transmitters. In case the air inside comes across any dielectric breakdown, still, the consequence is not fatal and is temporary. If the excess electric field is taken out, the air gets back to the normal state. There are also certain solid dielectric substances like glass and polyethylene that can endure permanent damage. 


What is the Dielectric Material?

We know that the dielectric constant is the ratio of the capacitance induced by two metallic plates in presence of an insulator, to the capacitance of the same place with vacuum or air. 

When a material is used for any insulation application, there is a need to have a low dielectric constant. 

The formula for dielectric constant goes as:

\[\epsilon\]  = \[\frac{C}{C_{0}}\], C\[_{0}\] = \[\frac{\epsilon_{0}A}{t}\]

Here:

C = capacitance used in material as the dielectric-capacitor

C0 = capacitance when the vacuum is used as dielectric

T = Thickness of the sample

A = Area of the plate

ε0 = Permittivity of free space (8.85 x 10⁻¹² F/m, i.e., Farad per meter)


Application of Dielectric Constant

This electrical property phenomenon is a dimensionless measurement. The standard tests to measure dielectric plastics are ICE 60250, ASTM D150, and a few more methods.

These methods comprise:

At first, a sample is a place between the 2 metal plates. Here, the value of capacitance is taken. Then, again the value is measured without the specimen between the two electrodes. The dielectric constant is nothing but just the value of their ratios.

  • Here, the test can be applied at a range of frequency values, actually within the 10Hz and 2MHz range.

  • The sample here should be larger and flat than the 50 mm circular electrode. 

FAQs (Frequently Asked Questions)

Question 1: What is the Significance of a Dielectric Constant?

Answer: The dielectric constant is a crucial property of a class of insulating substances. This material is the primary reason to measure the value of capacitance. 

A relative Permittivity is the ratio of Permittivity of a medium to that of the vacuum. One must design a capacitor accordingly.

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Since there is no specific symbol for the dielectric constant and it signifies as κ, ε, ε′ or εr.

The dielectric constant makes use of a capacitor to store energy, and it rises in equal proportion for any geometrical constants.

The size of the capacitor drops inversely with the dielectric. It is usual for a designer to look for substances that can minimize the size of the capacitor for any given value of the voltage signal. Here, ceramic is the best example to be used applicable to the value of thousands of dielectric constants.

Question 2: What is the Complex Dielectric Constant?

Answer: Complex dielectric constant has a wide range of applications due to its variation in the electric field. Here, this point is identified by a sine shaped waveform. This form is calculated as:

ϵ=ϵ′ + i⋅ϵ′′ϵ=ϵ′ + i⋅ϵ″

Here,

Real part ϵ′ϵ′ - denotes the permittivity component quantifying the stored energy (This part is directly propped to amplitude)

Virtual part ϵ′′ϵ″ - Dielectric loss-factor (Electric energy that is lost through the movement of ions/molecules)

This component also creates a difference in phase within the resulting polarization and field function. The void of this component will make the phase work perfect. These elements work because of the variation of frequency and the field.

The factors that affect the dielectric are:

  • Weathering and Deterioration

  • Presence of other materials in plastic

  • Structure & morphology 

  • Moisture & Temperature 

  • Voltage

  • Frequency - Dielectric constant decreases with the rise of frequency

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