In electrical engineering and physics, a conductor is a material with movable electric charges. All conductors have electric charges that are able move when electric potential differences (measured in volts) are applied to separate points of the material. The flow of charge, which is measured in amps, is called the electric current. In the majority of materials, direct current is proportional to voltage, as has been determined by the so-called Ohm's law, under the condition that temperature and material remain constant.
- Metals that Conduct Electricity
Most metals, such as, for instance, copper, steel and iron are good conductors. This the reason why all the parts of electrical equipment which need to allow a current to pass through are made of metal. Other metals, like silver and gold for example are also used as conductors on occasion, but they are quite expensive so they are only used for special purposes. Aluminum and other metals also conduct electricity, but none of them work as well as copper.
- Other Materials that Conduct Electricity
Metals are, however, not the only materials that can conduct electricity. Some other materials include carbon, salt and water solutions, plasma and conductive polymers. Even the human body can act as a conductor. This is one of the reasons why an electric shock can be felt when an electrical wire is touched.
Materials that do not allow electricity to flow easily through them are called insulators. Some materials often used for insulation in electrical circuits are rubber, plastic and silica. Glass is also an insulator, as are resins, cotton, card, paper and leather. Porcelain is also an insulator and is, or at least used to be, used to protect connections on power lines. Fiber glass and optical fiber (made from silica) are also good insulators, as is wood.