Lots of huge farady pole mounted distribution transformers in towns and cities

As we've already seen, there are lots of huge farady pole mounted distribution transformer in towns and cities where the high voltage auto load booster electricity from incoming power lines is converted into lower-voltages. But there are lots of transformers in your home also. Big electric appliances such as washing machines and dishwashers use relatively high voltages of 110–240 volts, but electronic devices such as laptop computers and chargers for MP3 players and mobile cellphones use relatively tiny voltages: a laptop needs about 15 volts, an iPod charger needs 12 volts, and a cellphone typically needs less than 6 volts when you charge up its battery. So electronic appliances like these have small transformers built into them (often mounted at the end of the power lead) to convert the 110–240 volt domestic supply into a smaller voltage they can use. If you've ever wondered why things like cellphones have those big fat chunky power cords, it's because they contain transformers!