Dielectric Polarization in Polar and Non-polar Material and Dielectric Constant

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What Do You Mean By Dielectric Constant?

Non-conducting substances, which can hold an electrostatic charge while dissipating minimal heat energy, refer to dielectric materials. There are several examples of dielectric materials, including air, plastics, glass, more. Different types of dielectrics possess different values for dielectric constant, dipole moment, and polarisation. Look at the concepts of polarization, what is dielectric constant, applications, and more. 

What is Dielectric Material?

A dielectric material or medium is an insulator kind that becomes polarised when it comes in contact with an electric field. Though a dielectric material is a poor conductor of electricity, it can support an electric field. Such kinds of materials are widely used in components like radios and capacitors. Some types of dielectric materials are solid, some are fluids, and some are gases in nature. Some of the examples of dielectric materials include:

  • Solid dielectric materials- Plastic, Ceramic, Mica, and Glass

  • Dielectric Liquid- Water

  • Dielectric Gas- Dry air

Applications of Dielectric Medium 

The dielectric material contains a high number of dipoles. Thus, when subjected to an external electric field, the positive end of one dipole gets induced towards the negative of another dipole. It forms a chain of alternate charge polarities throughout the dielectric material. Such kind of alignment leads to the formation of an electric field. Hence, among the different uses of dielectric materials, its main use is in the manufacturing of capacitors. 

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The above diagram shows the dielectric material. It shows when an external electrostatic field is applied, the dielectric medium gets polarised — additionally, dielectric stores electric charge when an electric field is introduced. 

Moreover, by introducing a dielectric medium between the capacitor plates, the capacity of the capacitor can be improved. Another best application of dielectric material is its use to store energy.

What is the Concept of Polarization in Polar and Nonpolar Molecules?

Insulators are bad conductors of electricity and heat due to the absence of free moving charges. Unlike metals, there is no flow of current in insulators when placed in an external electrostatic field. Instead of current flow, polarisation occurs in insulators on the application of the electric field. The extent of polarisation generally depends on the types of dielectric material. The charges in these materials do not move completely, but there is only a slight movement from their rest position. The polarity of molecules is generally decided by the nature of bonds existing in molecules. 

Dielectric Polarization in Polar Molecule

Polar molecules have permanent dipoles due to the bonds. Some of the examples of polar molecules are CO2, H2O, and more. However, the dipoles in a polar molecule are randomly oriented due to a thermal effect. That’s why the dipole moment of the polar molecules cancels out and hence, there is a zero-dipole moment. 

On the application of the electric field, the individual dipole moments align themselves in the electric field direction. According to the properties of dielectric materials, nature, bonds, and orientation remain constant inside the polar molecule. The extent to which the polar molecule gets polarised is directly related to the thermal energy and strength of the external field. 

Dielectric Polarization in Non-polar Molecule

A molecule without a dipole refers to a non-polar molecule. N2, O2, H2 are few examples of non-polar molecules. The charges are equally distributed in these types of molecules. On applying the electric field, the positive and negative charges having opposite polarities experience a force in the opposite direction. As a result, the electron cloud of a nonpolar molecule gets displaced towards attraction that causes an induced dipole moment. After acknowledging what is dielectric, students can understand why non-polar molecules lose polarity after the removal of the electric field. 

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The above diagram shows a nonpolar molecule unpolarised and polarised. The non-polar molecule gets polarised when an external electric field is applied to it. It results in distortion of electrons at the point of attraction. 

How To Calculate Dipole Polarization?

The application of dielectric constant is due to the introduction of the electric field across the material irrespective of whether a dielectric is polar or nonpolar. The polarisation referred to the dipole moment of a material per unit volume and denoted by:

P = \[\chi\]\[_{e}\]E

where \[\chi\]\[_{e}\] denotes the dielectric material property, also known as electric susceptibility of the dielectric medium. 

E represents the applied electric field

P represents the polarisation

Apart from the dielectric medium, another crucial parameter in calculating polarisation is the dielectric constant. The ability of the dielectric medium to store electrical energy when an electric field is applied refers to the dielectric constant.

FAQ (Frequently Asked Questions)

1. What is the Primary Difference Between Nonpolar and Polar Dielectric Polarization?

Ans: The primary differentiation between polar and the non-polar dielectric is the shape. Polar ones are asymmetric whereas non-polar ones are symmetric. Polar dielectrics are generally polar compounds which cannot conduct electricity whereas coming to non-polar dielectrics are the non-polar compounds that are unable to conduct electricity. The reason behind no electricity is that no free electrons are flowing that can conduct electricity. The main reason behind this could be the shape. The third main difference between polar and non-polar dielectrics is the polarity.

2. What is a Non-polar Material?

Ans: Non-polar materials are as the name suggests. These materials do not conduct any negative or positive charge in them. Non-polar dielectrics are made up of different non-polar molecules in which the positive charge centre of mass coincides with the negative ones. The dipole of the material is zero, and these are symmetric in shape. When we place these materials in the electric field, positive and negative charged molecules get displaced in the opposite direction. These non-polar dielectric materials cannot conduct electricity due to no availability of free electrons in it.