How does electricity get from the generating station to the outlet in my living room? — JJ, Arlington, MA
The generating station uses a large generator to transfer energy from a giant turbine to an electric current flowing through a coil of wire. Current from this generating coil then flows through the primary coil of a huge transformer, where it transfers its energy to the magnetic core of the transformer. The current then returns to the generator to obtain more energy.
The magnetic core of the transformer transfers its energy to a second current—one that is passing through the secondary coil of the transformer. Because this current consists of far fewer electric charges per second, each charge receives a very large amount of energy. This large energy per charge gives the current a high voltage and it flows very easily through a high voltage transmission line. Because the amount of power that a wire loses is proportional to the square of the current passing through it, this high-voltage, low-current electricity wastes very little power in the transmission line on its way across country to your city. When the current reaches your city, it passes through another transformer and its energy is transferred to a third current. The cross country current then returns through the transmission line to the original power station to obtain more energy from the first transformer.
This third current involves more charges per second, so each charge carries less energy and the voltage is lower. This medium voltage electricity travels to your neighborhood before passing through a final transformer. This final transformer is probably either a gray metal can on a utility pole or a green box on a nearby lawn. In passing through the final transformer, the current transfers its energy to a current which then enters your home. This last current delivers energy to your appliances and lights and then returns to the final transformer to obtain more energy.