Difference between Conductors and Insulators

Both conductors and insulators are extensively used in various fields of electrical and electronics engineering. In this article, we will compare and contrast the various features of conductors and insulators and how they function.

What is a Conductor?

The material which allows the electric current to pass through it is known as conductor. In other words, the material which has less than 4 electrons in its outermost shell is known as conductor.

When electric potential is applied across a conductor, the electrons can freely move from atom to atom. In a conductor, the valance band and the conduction band are overlapped each other. As a result, there is no forbidden energy gap, thus the free electrons in the valance band can move easily in the conduction band. The conductors have very low resistance, consequently, on the application of voltage, the electrons can freely move from atom to atom.

Conductors are mainly used to make connecting leads, transmission lines, windings, etc. The examples of conductors are silver, copper, aluminium, etc.

What is an Insulator?

The materials that do not allow the electric current to pass through them are known as insulators. The insulators have more than 4 electrons in their outermost shell. In case of insulators, the electrons cannot move freely due to very strong covalent bond between the atoms. Consequently, the resistivity of the insulators is very high.

Also, for insulators, the forbidden energy gap between the valance band and conduction band is very large due to which the valance electrons in the valance band cannot jump into the conduction band. The insulators are used for providing insulation in the electrical equipment such as insulation coating of wire, plug tops, transmission line insulation, etc. Some of the examples of insulators are paper, mica, porcelain, wood, glass, etc.

Difference between Conductor and Insulator

The following table highlights the key differences between conductors and insulators −

Parameter	Conductor	Insulator
Definition	The materials that easily allow the electric current to pass through them are known as conductors.	The materials that do not allow the electric current to pass through them are known as insulators.
Electric conductivity	Conductors possess very high electric conductivity.	The electric conductivity of the insulators is negligible.
Resistance	For the conductors, the resistance for the flow of electric current is low.	For the insulators, the electric resistance is very high.
Electron movement	In case of conductors, the electrons can move freely atom to atom.	In insulators, the electrons cannot move freely.
Number of electrons in outermost shell	Conductors have less than 4 valance electrons in the outermost shell.	Insulators have more than 4 electrons in the outermost shell.
Temperature coefficient	Conductors have positive temperature coefficient of resistance, i.e. the resistance of the conductor increases with the increase in temperature.	Insulators have negative temperature coefficient of resistance which means the resistance of insulators decreases with the increase in temperature.
Electrons in conduction band	The conduction band of conductors is full of electrons.	For insulators, the conduction band remain empty.
Electrons in valance band	For conductors, the valance band remains empty.	The valance band of insulators is full of electrons
Forbidden energy gap	In case of conductors, there is no forbidden energy gap, i.e., the conduction and valance bands overlap each other.	Insulators have large forbidden energy gap.
Thermal conductivity	Conductors have high thermal conductivity.	Insulators have low thermal conductivity.
Electric field	The electric field exists on the surface of conductor and it is zero inside the conductor.	In case of insulators, the electric field does not exist.
Covalent bond	There is very weak covalent bond between the atoms of the conductor.	The covalent bond between the atoms of an insulator is very strong.
Conductivity	Conductors have very high conductivity, i.e. they provide ease to the flow of current.	The insulators have very low conductivity.
Distribution of capacitance	For the conductors, the capacitance remains the same at all the points.	For the insulators, the capacitance is zero.
Resistivity	The resistivity of the conductors vary from high to low.	The resistivity of insulators is relatively high.
Examples	The metals such as silver, gold, copper, aluminium, etc. are the examples of conductors.	Examples of insulators are rubber, wood, paper, ceramic, mica, glass, porcelain, etc.
Applications	Conductors are extensively used for making electric cables, wires, connecting leads, transmission conductors, windings, etc.	Insulators are used as covering for cables and wires, transmission conductor insulators, for making switches, sockets, plugs, etc.

Conclusion

As is evident from the above table that there are several differences between conductors and insulators and how they function. The key difference between them is that conductors allow electric current and heat to pass through them, while insulators restrict the flow of electric current and heat through them.