Electrostatics

Dielectric Constant

Take a little visit to your kitchen, did you actually see the fired cookware’s or utensils have some shared trait with glass, plastic, mica or even the air? Did you actually consider building an electronic segment out of them? Most likely not! Since the property of these materials is frequently ignored. In this article, we shall discuss dielectric constant in detail.

Dielectric Constant

What is Dielectrics?

A dielectric (or dielectric material) is an electrical cover or insulator. It is polarized by applying an electric field. At the point when a dielectric material is set in an electric field, electric charges don’t move through the material. As they do in an electrical transmitter however just marginally move from their normal harmony positions causing dielectric polarization.

In view of dielectric polarization, positive charges are to dislodge towards the field. Negative charges move toward the path inverse to the field. For instance, if the field is moving in the positive x-pivot, the negative charges will move in the negative x-axis. This makes an inward electric field that decreases the general field inside the dielectric itself. If a dielectric is made out of pitifully fortified atoms, those particles become not on polarizes. Yet additionally, it reorients so their evenness aligns to the field.

The investigation of dielectric properties concerns stockpiling and dissemination of electric and attractive energy in materials. Dielectrics are significant for clarifying different wonders in hardware, optics, strong state material science, and cell biophysics.

Terminology of Dielectric

In spite of the fact that the term encasing suggests low electrical conduction. Dielectric ordinarily implies materials with a high polarizability. The last is communicated by a number is the relative permittivity. The term encasing is commonly used to show electrical hindrance while the term dielectric is utilized to demonstrate the energy putting away limit of the material by methods for polarization. A typical illustration of a dielectric is the electrically protecting material between the metallic plates of a capacitor. Also, the polarization of the dielectric by the applied electric field builds the capacitor’s surface charge for the given electric field strength.

The term dielectric was begotten by William Whewell (from dia- + electric) because of a solicitation from Michael Faraday. An ideal dielectric is a material with zero electrical conductivity, wonderful transmitter with infinite electrical conductivity. In this manner showing just an uprooting flow. Thus, it stores and returns electrical energy as though it were an ideal capacitor.

Dielectric Constant

The dielectric constant of a substance is the ratio of the permittivity of the substance to the permittivity of the free space. It shows the extent to which a material can hold electric flux within it.

Dielectric Constant Formula

Mathematically dielectric constant is:

k= \(\frac{\epsilon_{0}}{\epsilon }\)

here,

  • κ is the dielectric constant
  • \(\epsilon\) is the permittivity of the substance
  • \(\epsilon_{0}\) is the permittivity of the free space

The Theory Behind Dielectric Constant

This is a prime boundary to describe a capacitor. A capacitor is an electronic part intended to store electric charge. This is broadly built by sandwiching a dielectric protecting plate in the middle of the metal conducting plates. The dielectric property assumes a significant part in the working of a capacitor.

The layer comprised of dielectric material chooses, how adequately the capacitor can store the charge. Picking the correct dielectric material is significant. Along these lines, we can likewise characterize it as ‘the proportion of the electric field without a dielectric \(\epsilon_{0}\) to the net field with a dielectric \(\epsilon\).

k= \(\frac{\epsilon_{0}}{\epsilon}\)

Here, the estimation of E0 consistently more prominent than or equivalent to E. Along these lines, the estimation of a dielectric steady is consistently more prominent than 1.

The more prominent the estimation of κ more charge can be put away in a capacitor.

In the capacitor, the capacitance is:

C = \(kC_{0}\)

The relative permittivity of a dielectric substance is also called a Dielectric Constant and is expressed using the Greek letter kappa ‘κ’.

Consequently, filling the hole between the plates totally by dielectric material will expand its capacitance by the factor of dielectric steady worth.

Therefore, in the parallel plate capacitor, the capacitance is:

C = \(\frac{k\epsilon _{0}A}{d}\)

Where,

  • C is the capacitance of the parallel plate capacitor.
  • κ is the dielectric constant.
  • \(\epsilon_{0}\) is the permittivity of the free space.
  • A is the area of parallel conducting plates
  • D is the separation between parallel conducting plates

The capacitance worth can be maximized by expanding the estimation of the dielectric constant. Also, by diminishing the partition between the parallel leading plates.

As it is the proportion of two like substances, it is a unitless and dimensionless quantity.

Factors Affecting Dielectric Constant

The dielectric consistent relies upon different factors like,

  • Frequency: The recurrence of the applied voltage is one of the variables influencing dielectric constant. As the frequency of the applied voltage builds, the estimation of the dielectric consistent gets non-linear.
  • Applied voltage: When an immediate flow voltage is applied, the estimation of the dielectric constant diminishes. It is while applying to exchange flow voltage that would build the estimation of the dielectric constant.
  • Temperature: When the temperature is low, the arrangement of the atoms in the dielectric material is troublesome. By expanding the temperature, the dipoles in the dielectric material become prevailing bringing about an expansion in the dielectric constant. This temperature is the transition temperature. In the event that the temperature transcends the progress temperature, at that point there will be a gradual abatement in the dielectric constant.
  • Humidity and dampness: The strength of the dielectric material diminishes when either the stickiness or the dampness expands.
  • Heating effect: When the dielectric material is warmed, the dielectric misfortune happens. Dielectric misfortune is characterized as the scattering of energy as warmth when there is a development of the atoms in the material, as it is presented to the substituting flow voltage. This happens as the material assimilates electrical energy.
  • The structure and morphology of the material additionally impact the dielectric steady.
  • Deterioration and enduring of the material additionally influence the dielectric steady.

FAQs about Dielectric Constant

Q.1. Define the polarization of a dielectric material.

Answer: The polarization of dielectric material is characterized as the cycle of creation of electrical dipoles inside the dielectric. This is done by the utilization of an outer electrical field. Dielectric polarization happens when a dipole second is shaped in a protecting material on account of a remotely applied electric field. At the point when a flow cooperates with a dielectric (protecting) material, the dielectric material will react with a move in control circulation with the positive accuses adjusting of the electric field and the negative charges adjusting against it. Thus, by exploiting this reaction, significant circuit components, for example, capacitors can be made.

Q.2. What are the four polarization mechanisms?

Answer: Given below are the four polarization mechanisms:

  • Electronic polarization
  • Orientational polarization
  • Ionic polarization
  • Space-charge polarization

Q.3. What is the difference between active and passive dielectrics?

Answer: The contrast among active and passive dielectrics is that the dielectrics which adjust effectively for the capacity of electrical energy are active dielectrics. While the dielectrics that confine the capacity of electrical energy are passive dielectrics. Piezoelectric is an illustration of a functioning active dielectric while the glass is an illustration of a passive dielectric.

Q.4. List the various breakdown mechanisms in dielectrics.

Answer: Given below are the various breakdown mechanisms in dielectrics:

  • Intrinsic and avalanche breakdown
  • Chemical and electrochemical breakdown
  • Thermal breakdown
  • Defect breakdown
  • Discharge breakdown
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