When a gas is heated to a very high temperature, its atoms may lose electrons and so become electrically charged. It is then said...Read More >>When a gas is heated to a very high temperature, its atoms may lose electrons and so become electrically charged. It is then said to be "ionized" and is able to conduct electricity. In this state, the gas is called a plasma. Lightning is a familiar example of plasma. Typically it may carry a current of 10,000 amps at 100 million volts.Electricity flows in a current when electrons are free to move through certain materials, known as conductors. Most metals, especially silver and copper, have electrons that can move easily, so metals make particularly good conductors of electricity. Carbon is an example of a non-metallic conductor—but only in certain forms. Graphite is a good conductor, but diamond is not. A substance in liquid form, either molten (melted) or in solution, that can conduct electricity is called an electrolyte.
Cross-section through an electric cable. The copper wires are surrounded by sheaths of plastic, a material that does not conduct...Read More >>Cross-section through an electric cable. The copper wires are surrounded by sheaths of plastic, a material that does not conduct electricity and so acts as a useful insulator.
In substances such as rocks, wood, most plastics, rubber and glass, there are no—or very few—electrons free to move. These materials reduce or prevent the flow of electricity and are known as insulators. But they are just as useful: rubber and plastics are used to cover wires and so protect us from electric shocks.
Copper is one of the best affordable conductors, and is the standard to which other conductors are compared. Silver is an even better conductor, but is too expensive to use for wiring. Aluminium has 62% the conductivity of copper.
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