Various materials are often researched for their conductive properties. The materials are given numbers that tell their relative rates of conduction. Materials are compared to silver(coefficient of heat conduction of 100). The coefficient of some other products are copper(92), iron(11), water(0 .12), wood(0.03). A perfect vacuum has a conduction coefficient of zero.
Materials that are poor conductors of heat are insulators. Air is an awesome insulator when it is locked in an enclosed space. It has a conduction coefficient of .006. the air locked between feathers, fur, and fibers is what allows those materials to keep us so warm.
So, with a charge, an insulator does not allow electrons to move freely along it and prevents heat conduction, but metals do allow electrons to move readily. Consequently, if a charged rod touches an insulated metal object, some of the charge will pass and the metal object receives a charge via conduction. The charge will cover the total surface of the conductor. Then, if the charged object touches a large body via a wire, it becomes grounded and looses its charge.
What is conduction, well it can be the transfer of heat or the transfer of a charge. Both happen because of a substance’s readiness to allow molecules to move.
We’ve also recorded an entire episode of Astronomy Cast all about Magnetism. Listen here, Episode 42: Magnetism Everywhere.