Those materials which don’t allow the passage of electricity through them are known as insulators. We can call them as the poor conductors of electricity. Some of the common examples of the insulators are rubber, mica wax, glass etc. The reason that the free electron count in these substances is almost zero or in other words we can say that it is negligible.
There is no doubt that in insulators electrons are also bound to atoms. In insulators the electrons remain near the main nuclei i.e. the parent nuclei.
The other name of insulators is dielectric. Dielectrics are insulators but they can transmit charge when an external electric field is applied to these dielectrics.
The proper scientific definition of dielectric is:
‘Those insulating materials which transfer the electric effects without conducting are dielectrics’.
When we apply the electric field some charges called as induced charges are produced on its surface. Due to these induced charges, it starts showing some conducting properties.
