Conductors and insulators.

Conductors	Insulators
·         Those substances through which electricity can flow are called conductors. ·         Electrical resistances of conductors are very low. ·         They contain large number of free electrons. ·         Generally metals are conductors. E.g. silver, copper, aluminium	·         Those substances through which electricity cannot flow are called insulators. ·         Electrical resistances of insulators are infinitely very high. ·         They do not contain free electrons. ·         Generally non – metals are insulators. E.g. wood, rubber, plastic