Compare and Contrast Conductors and Insulators

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In physics and electrical engineering, all materials can be classified on the basis of the band theory of solids i.e conductors and insulators.

In other words, based on the fact that whether the material is a good conductor of electricity or not, they can be bifurcated into mainly two special groups.

Before going into a deep discussion, let me give you a brief review of the two in a tabular form. Let’s dive right in!

Difference Between Conductors and Insulators

	Conductors	Insulators
1.	Materials that conduct electricity are conductors.	Materials that do not conduct electricity are insulators.
2.	In conductors, the electric field can only exist on the surface of the material but remains zero inside it.	In insulators, the electric field can neither exist on the surface nor inside the material.
3.	The electric charge (electrons) can move freely inside the conductors.	The electric charge (electrons) cannot move freely inside the insulators.
4.	They can store energy.	They cannot store energy.
5.	They show very high conductivity and low resistance.	They show negligible conductivity and very high resistance.
6.	The resistivity of conductors can vary from low to high.	Insulators have very high resistivity.
7.	In the case of conductors, the covalent bonds are quite weak.	In the case of insulators, the covalent bonds are quite strong.
8.	In conductors, the conduction band is full of electrons and the valence band is almost empty.	In insulators, the valence band is full of electrons and the conduction band is almost empty.
9.	Due to the overlapping between the conduction and valence band. Hence, there is no forbidden gap in conductors.	Since there is no overlapping between the conduction and valence band, Hence, there is a large forbidden gap in insulators.
10.	In the case of conductors, the temperature coefficient of resistance is positive.	In the case of insulators, the temperature coefficient of resistance is negative.
11.	Examples of conductors include silver, aluminum, iron, etc.	Examples of insulators include rubber, wood, paper, etc,

What are Conductors?

Conductors are the materials that allow electric current or sometimes heat to pass through them. Hence becoming electrically conductive in nature.

Not to mention, materials that are primarily made of metals are the best available conductors. Conversely, Graphite is the only non-metal that can conduct electricity.

In conductors, free electrons can move freely anywhere inside a conducting material. WHY? Because there is an overlapping between the valence band and conduction band of the material. Therefore, as a result, there is no forbidden gap between the layers of the atomic structure of the conductors.

Just because the conductors have very high conductivity, they have very low resistance. In other words, due to low resistance, electrons can move freely inside a conductor, of course, when a potential difference is applied across them.

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We will talk about examples of conductors in the later section. Before that let’s get to know a bit about the properties of a good conductor.

Properties of Conductors

There are so many properties of conductors. However, at the equilibrium condition, an electrical conductor shows the following properties.

They have low resistance and high conductivity.
The electric field inside both conductors and insulators is zero.
Covalent bonds are weak, therefore, can be easily broken.
The resistivity of conductors can vary from low to high.
The temperature coefficient of resistance of the conductor is always positive.
The charge density inside a conductor is always zero.

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Types of Conductors

As I have mentioned in the conductor vs insulator (tabular) part, the resistivity of the conductor can vary from low to high. Therefore, based on the conductor definition due to its resistivity, they can be bifurcated into two categories. These are:

Low resistivity/high conductivity materials
High resistivity/low conductivity materials

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Examples of Conductors

Not to mention, the best conductor of electricity is silver. However, silver is not the most ideal choice for making a conducting material. WHY? Because it is too expensive to be used for common purposes.

Apart from silver being a good conductor of electricity, here is the list of the top 10 examples of conductors in daily life.

Aluminum
Steel
Mercury
Brass
Graphite
Gold
Copper
Bronze
Iron
Platinum, etc.

Applications of Conductors

Conductors are quite useful in our day-to-day life. In other words, you can see so many real-life applications of conductors around you. Here is a list of conductors which are the most used ones.

Copper is commonly used for making electrical appliances such as motor winding, cables, etc.
Mercury is used as a conducting material in a thermometer.
Silver is used for making satellites.
Aluminum wires for power transmission and distribution.
Aluminum foils for food storage, etc.

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What Are Insulators?

Insulators are materials that do not allow heat or electricity to pass through them. Not to mention, the electric current does flow through an insulator. WHY? Because there is no material that can be a perfect insulator. Unlike conductors, materials that are primarily made of non-metals are the best available insulators.

In insulators, free electrons cannot move freely anywhere inside an insulating material. WHY? Because there is no overlapping between the valance band and conduction band of the material. Therefore, as a result, there is a large forbidden gap between the layers of the atomic structure of the insulators.

Just because the insulators have very low (negligible) conductivity, they have very high resistance. To put it differently, due to high resistance & large forbidden gap, electrons can never move freely inside an insulator.

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On the contrary, if the potential difference of a sufficiently large voltage is applied across the insulator, the applied electric field can tear away the electrons from the atoms of an insulator.

Hence, an insulator becomes a conductor. This property of an insulator is commonly known as the breakdown voltage of an insulator.

Properties of Insulators

There are so many properties of Insulators. However, at the equilibrium condition, an insulating material shows the following properties.

They have high resistance and low conductivity.
The electric field inside both conductors and insulators is zero.
Covalent bonds are strong, therefore, too hard to be broken.
They have high resistivity.
The temperature coefficient of resistance of an insulator is negative.
At the breakdown voltage, an insulator can become a conductor.

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Types of Insulators

Based on low to medium to high voltage systems, 5 types of insulators used in transmission lines are as follows:

Pin Insulator
Suspension Insulator
Strain Insulator
Stay Insulator
Shackle Insulator, etc.

Examples of Insulators

Insulators are nothing but a barrier or a layer between the conductors to keep electrical current under control. Well, what materials are good insulators? ANY IDEA?

Here is the list of the top 10 examples of insulators that are proactively used in our day-to-day life.

Glass
Rubber
Oil
Air
Dry wood
Fiberglass
Quartz
Diamond
Plastic
Asphalt, etc.

Applications of Insulators

Again, there are so many applications of insulators in our everyday life. In fact, if you take a close look, you will find uses of insulators in your home too. Here is a list of insulators that are the most used ones.

Rubber is the common insulating material used for making slippers, vehicle tires, or fire-resistant clothes, etc,
PVC, Kapton, Teflon, etc for providing a protective layer to the electrical wires.
Fiberglass or plastic to make printed circuit boards, etc.

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Frequently Asked Questions

1. What does an insulator do?

Ans. Well, what an insulator does is oppose the flow of current. In other words, an insulator is a material that blocks or hinders the flow of electric current or heat.

2. What conducts electricity the best?

Ans. Superconductors conduct electricity the best. WHY? Because superconductors show zero resistance toward thermal heat or electricity.

3. Is plastic a conductor or insulator?

Ans. Well, plastic is by far an excellent example of an insulator. WHY? Because they can easily trap the heat inside themselves. Therefore, as a result, they are mostly used for making coffee cups.

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