Difference between Conductor and Insulator

Updated: Aug 20

The major difference between a conductor and an insulator is on the basis of the property of passing of current through them. The conductor easily allows the electric current through it. On the other hand, an insulator impedes the flow of current through it.

There are three types of materials widely used in electrical engineering, namely conductors, insulators, and semiconductors. First, we will discuss what is a conductor and an insulator. We will then discuss the difference between the conductors and insulators.

What is a Conductor?

A material that easily passes the electric current through it is called a conductor. Generally, all metals are good conductors of electricity. Also, electrical conductors are good conductors of heat.

The electric conductors have free electrons and it leads the flow of electric current through them. The flow of electrons through the conductor takes place with the application of a voltage across it.

If we compare the electric conductivity of the conductor, semiconductor, and insulator, the conductivity of the conductor is the highest among all of them. The conductors have more free electrons compared to insulators and semiconductors. Thus, the higher the number of free electrons cause more electric current through the material.

If the number of electrons in the outermost orbit of an atom is less than four, then we can say that the material is a good conductor of electricity. The less number of electrons in the outermost orbit shows that there is a less forbidden gap, and the electrons can easily jump from the valance band to the conduction band on the application of voltage or external energy.

The forbidden gap between the valance band and the conduction band is almost nil, and both bands are overlapped in the conductor,

Silver, copper, aluminum, gold, and platinum are a few examples of conductors.

What is an Insulator?

An Insulator has just the opposite characteristics of a conductor. The insulator does not allow the current through it. The electrons in the outermost orbit of an insulator are closely packed and it is very difficult to release these electrons from it.

The insulators have four electrons in their outermost shell and there are negligible free electrons in the material.

There is a wide energy gap(forbidden energy gap) between the valance band and the conduction band in an insulator.

The flow of electric current depends on the gap between the conduction and valance band, and this gap for insulating material is very wide. Hence, the insulators are bad conductors of electricity.

Wood, paper, air, mica, glass, porcelain, plastic & rubber, are examples of insulators.

Difference between Conductor and Insulator

Basis of Difference




It allows the flow of electric current through it.

It restricts or impedes the flow of electric current.

Number of free electrons

It has less than 4 electrons in the outermost shell.

It has more the 4 electrons in the outermost shell.


Conductors have very high conductivity compared to insulators.

The conductivity of insulators is almost zero.


Very Low

Very high

Temperature coefficient

The resistance of the conductor increases with an increase in temperature. Therefore, the conductors have a positive temperature coefficient(PTC).

The resistance of the insulator decrease with an increase in temperature. Therefore, the insulators have a negative temperature coefficient(NTC).

Conductivity of heat

High thermal conductivity.

Low thermal conductivity

Inside electric field


There exists an electric field inside an insulator.

Forbidden energy gap

Almost zero

Large forbidden gap

Electrons in Valance band


Full of electrons

Electrons in the Conduction band

Full of electrons.



Copper, silver, aluminum, gold, etc. are examples of conductors.

Wood, paper, rubber, plastic, mica, glass, etc.


Used to make electrical wires, and busbars

It supports the conductor and provides insulation between the live conductor and the earth.

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