Are gold wire and ice and rubber and yarn and paperclips conductors?

Answer 1

We classify materials into three general categories -- conductors, semi-conductors and insulators. In general, a conductor conducts even below room temperature. A semi-conductor is a poor conductor at room temperature and its conductivity increases with rising temperature. An insulator is a very poor conductor even at rising temperature.

A gold wire is made of gold, which is a metal. Metals are mostly conductors.

Ice, rubber and yarn don't conduct very well. They are insulators. Note that ice disappears at above-freezing temperature. A paper clip without an insulating coating is a conductor. If it is sheathed with a plastic coating, it is more likely an insulator, depending whether one applies electricity at the exposed ends or not -- the exposed ends can form a conductor.

A reliable way to tell whether it is safe to apply a voltage to an item is to check out the arrangement with an ohmmeter. Very loosely defined, a mega-ohm or above is a poor conductor; a giga-ohm is in the insulator territory. A good conductor will read a resistance below a kilo-ohm.

I have not discussed sheet resistance or resistivity; it is a more advanced topic.