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How Electricity Works

Operating an electrical switch is like turning on a water faucet. Behind the faucet (or switch) there is a source of water (or electricity), a way to transport it, and pressure to make it flow. The faucet's water source is a reservoir or pumping station. A pump provides enough pressure for the water to travel through the pipes. The switch's electrical source is a power generating station. A generator provides the pressure for the electrical current to travel through electrical conductors, or wires.

Three factors determine the resistance of a substance to the flow of electricity.

  • What it is made of.
  • Its size.
  • Its temperature.
Substances with very little resistance to the flow of electricity are called conductors. Examples are metals. Substances with a high resistance to the flow of electricity are called insulators. Examples are glass, porcelain, plastic, and dry wood.
Pure water is a poor conductor of electricity, but small amounts of impurities, such as salt and acid, make it a ready conductor. Perspiration contains both water, salts, and impurities. When the skin is dry, it is a poor conductor of electrical current. When it is moist, it readily conducts electricity. Use extreme caution when working with electricity where there is water in the environment or on the skin. This concept applies to other items such as wood. When wood is dry it is a poor conductor, when wet wood conducts electricity more readily.


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