Question

What are energy bands? Write any two distinguished features between conductors, semiconductors and insulators on the basis of energy band diagrams.

Answer 1

Hint: Energy band here refers to the energy level of the electrons and their position and also, the distinguished features of conductors, semiconductors and insulators can be shown in terms of the valence band and the conduction band.

Complete answer:
In the case of a solid, the energy levels of the electrons lie within a certain range. These energy levels exist as a band and incorporate electrons that fit in their energy level. These bands are known as an energy band.

The two distinguishing features between conductors, semiconductors and insulators on the basis of energy band diagrams are as follows:
-In a metal – or a conductor – the conduction band and the valence band appear to near overlap – or overlap – while in the case of insulators and semiconductors, the energy gap is visible. In insulators, the gap is higher and in semiconductors, the gap is small.

-For the purpose of electrical conduction, the conductors have a sufficient number of electrons to perform that. However, the insulators have no such electrons and so they cannot perform electrical conduction. The semiconductors have few electrons available for such electrical conduction.

Note:In many places, the energy gaps are also given a number to represent the gap. For example, the energy gap in semiconductors is less than $3eV$ and in insulators is more than $3eV$. In conductors, it is zero. Also, along with electrical conductions, the effect of temperature is also understandable using the energy band diagrams.