Conductors and Insulators

Author: E.E. Kimberly

An electromotive force applied to the ends of a copper rod will cause a flow of electrons from atom to atom in the rod, because the copper atom yields its electrons readily. The iron atom yields its electrons less readily; so, if the rod were of iron, less current would flow. If the rod were of wood or glass, still less current would flow because atoms of those substances yield their electrons very reluctantly. A substance that yields its electrons readily is called a conductor, and one that yields them reluctantly is called an insulator. Throughout the range of possible substances to which electromotive forces may be applied, there is no definite dividing point to distinguish conductors from insulators. No substance is a perfect conductor, and none is a perfect insulator. Silver is the best conductor known. Copper, while not so good a conductor as silver, is most commonly used because of its relatively low cost. Dry wood, porcelain, glass, and many synthetic materials are very good insulators.