Why is graphite a good conductor of electricity?

Explanation

In diamond, all the carbon atoms are `sp^(3)` hybridised. Each carbon atom is tetrahedrally bonded to four C-atoms. It forms three dimensional network structure. Since there is no free electrons, therefore, diamond is a bad conductor of electricity. In graphite, each carbon atom is `sp^(3)` hybridised and each carbon atom is linked to three other carbon atoms by covalent bonds. Here fourth valence electron, is free to move. Thus, it makes graphite a good conductor of heat and electricity.