In general, metals make good conductors of electricity. These include copper, gold, silver and aluminum. Copper is a common conductor of electricity used in industrial applications because it is inexpensive to acquire, especially in comparison to gold and silver. Aluminium is not as efficient in conducting electricity as copper is.
Conductors are so-named because they permit the flow of electricity, or the movement of electrons from one atom to another. While metallic substances make good conductors of electricity, non-metallic substances usually do not. These include air, glass, wood, plastic and rubber. Materials that are not good conductors of electricity are commonly known as insulators. Insulators restrict the flow of electrons from one atom to another. Some of the strongest insulators include glass, pica and quartz. Insulators are used where it is necessary to protect or shield from electricity, such as electrical cords. The covering of the cord is the insulator, which prevents electricity from flowing to the outside of the cord. The inside of the cord contains the conductor, which allows electricity to flow and the appliance to function.The relationship between conductors and insulators can be summarized in terms of their resistance to electrical current. Conductors have low resistance to electrical current. Insulators have high resistance to electrical current.