Polar and Non-polar Dielectrics

Polar and non-polar dielectrics is an essential aspect of Physics and a vital topic in Engineering, Chemistry, and Mathematics. 

Impurities in a crystal lattice can cause the polarisation of molecules contained within it to change. Exploring this area will help understand dielectrics and other related topics such as capacitors and conductors.

Polar and Non-polar Dielectrics: Meaning

Polar Dielectrics

Polar dielectrics are substances attracted to the electric field because of an electric charge. The same polarity attracts the molecules of these materials. The material is dipoles or polar, but the substances attract one another because the dipoles are opposite in sign. Polar dielectrics must be separated from non-polar dielectrics as they have different properties and behaviours.

The main properties of a polar dielectric are:

• The dipoles are of opposite signs – positive and negative charges
• The dipoles are positioned in the same direction (two north poles together or two south poles together, etc.)

Non-polar Dielectrics

In non-polar dielectric substances, the molecules are not polarised, and there is no charge attraction. In addition, non-polar substances do not contain a permanent dipole. Therefore, the molecules have no alignment, and they do not produce an electric field. They cannot be used as dielectrics in capacitors because they are polar.

The main properties of a non-polar dielectric are:

• The molecules in the substance are not polarised
• There is no alignment or order of the molecules

To understand polar and non-polar dielectrics, consider this scenario: A football is placed on a table with a positive patch at one end and a negative patch at another. If you now throw the ball using an electrical field, you will find that the ball moves in a way that follows the direction of your electrical field; it has been shown many times that this is due to an interaction between them. 

If you were to throw a charged football at an isolated table, it would stay on the table and not move because it is a dielectric. If, however, you threw an uncharged football at a small table, it would move because it is a non-polar material. This is the same with wood, water or oil substances.

Both polar and non-polar dielectrics have different uses. For example, contrasting materials are perfect for storing energy in capacitors that store electrical charges. Still, their molecules align in the same direction, which makes them not very good for other types of conductors such as wires.

Applications of Polar Dielectrics

1) Crystals

2) Optics – making polarised lenses to reduce light rays, or to concentrate them.

3) Wire insulation

4) Capacitors – storing and releasing energy by holding onto the electrical charge of a battery. 

5) Double-Layer Capacitors – used to store electric charge in plates and store it for use. If a capacitor is connected in parallel with another capacitor, the charges in both can be doubled. 

6) Antistatic Devices- against static electricity build up for avoiding builds up of unbalanced charges.  Anti-static devices are used to avoid discharges from static electricity build up from clothes as well as other materials that build up static charges when rubbed together.

Applications of Non-Polar Dielectrics

1) Electrical Insulation (Wires)

2) Conductors – similar to wires but much better at conducting the flow of electricity.  The layer of insulation is used for separating the two. Conductors are used for both single and multiple electrical circuits in electronics.  They are used to help reduce static electricity build up from materials like clothes and carpets in electrical appliances and television’s.

3) Solid-State Relays – used to switch the flow of electricity in electronics. Relays take the current flowing through one terminal, branch off it through another terminal, then send it back again through one more terminal.

Significance of the Attractiveness of Polar and Non-Polar Dielectrics

Most of the time, when a material is called a dielectric, it is considered to be non-polar. However, the term dielectric is also used to denote a substance with an electric charge in some instances. Dielectrics are substances that tend not to allow charged particles of one polarity to go through them, but, in most cases, they do not have an electric charge themselves.

Conclusion

The significance of dielectrics and the attraction they have to each other is that they can be used to store energy and have varying degrees of strength. Materials such as oil, wood, and water are polar because their molecules align and can store energy but are not very good conductors. Other non-polar materials, such as concrete and ceramic, contain non-aligned molecules which do not create an electric field, unlike polar materials. Because of this, it is often seen that when a material is made into an object (such as a wire or stone), it will have more resistance and can handle more energy.