Is a diamond a insulator or a conductor?
Diamond is a good thermal conductor. But it is an excellent electrical insulator.
first of all we need to know what is insulator and what is conductor, insulator is a substance in which there is no free electrons in the conduction band ,electrons in conduction band are responsible for a substance to be conductor. now as there in diamond all the atoms are closley packed and are bounded by carbon carbon bonding there fore due to this there is no free electron and hence diamond is an insulator.
A carbon rod may be an insulator or a conductor. It depends on which allotrope of carbon we're talking about. Electricity can travel through a graphite (carbon) rod easily, but it cannot travel through a diamond rod. Both graphite and diamond are carbon, but the former is a conductor while the latter is an insulator.