In the last article, I have discussed about the conductors, semiconductors and insulators. Today I will discuss why insulators do not conduct electricity or why insulator is insulator?

As I have already discussed that there is energy band gap between valence band and conduction band. This energy band gap is very large in case of insulators. It may be minimum of 3 electron volt or more. Therefore electrons can not be excited to conduction band from valence band. This is because electrons requires energy to get excited. The energy required is very high.

Thus insulators do not conduct electricity or insulators are insulators because of very large energy band gap between the valence band and conduction band.

Examples of insulators: wood, plastic