[Physics Class Notes] on Dielectric Pdf for Exam

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 behavior 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, let us define the dielectric constant:

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

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.

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 its 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:

[k=frac{Cepsilon _0A}{d}]and[k=frac{C_0}{C}]

()

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 placed 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 2 MHz range.

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

A dielectric material is used to split the conductive plates of a capacitor.  This insulating material considerably determines the properties of a component. The dielectric consistent of a material determines the amount of electricity that a capacitor can store whilst voltage is applied. 

A dielectric material becomes polarized whilst it is exposed to an electric field. When polarization occurs, the powerful electric area is reduced. Since the permittivity of a material is depending on frequency and temperature, the dielectric consistent is generally given at precise conditions, generally at low frequencies. Moreover, the dielectric consistent of a material is usually given relative to the permittivity of free space.