I was taught in school about Edison and the invention of electricity, and how he invented so many things that we take for granted today. Follow me back in time with some history that is very rarely mentioned because at that time Edison was a very wealthy and respected citizen who was listened too, and a man named Tesla was basically ignored!
The country in 1882 had all its electricity supplied by one method, and that was direct current. Direct current flows in a uniform direction, staying within the limits of one polarity, and alternating current flows between the two poles, positive and negative, and it does this at a specific frequency, usually sixty times a second in a sinusoidal pattern (meaning sine wave-like). Thomas Alva Edison had been the manufacturer up until that point in history of the system that carried the current to the households of America.
Direct current was not practical for traveling long distances to houses, and required transformers to boost the signal several times along the path from the generating plant to a person's house or to a building because of the resistance of the direct signal through the copper wires they used. This required costly and bulky equipment to have to be installed along the path to one's house, and caused electricity to be expensive and therefore rare. Edison was the leader in the production and maintenance of the equipment that his transmission system required; he designed and was responsible for the building of the system.
As I described, Tesla offered the idea of a rotating magnetic to produce AC (altenative current).
This meant that the voltage could be changed without serious loss of energy, using transformators, which are not costly, and quite small. Now I'll have to mention a little physics:
The loss of energy in the moving of electricity is the thermal energy created in the wires. This energy depends on the resistance of the wires (R), which is a constant, and the size of the current (I)
P= (I*I)*R <- The units are watts
The station produces constant power. Which means you can't change the value of I*V. But if you enlage V, using transformators, 'I' is reduced, and thus, the thermal energy lost (I*I)*R is much, much smaller! And a lot of money is saved! Another transformator is needed to reduce the voltage in the household, so it won't be dangerous. Voila!
So really, Tesla's method was much more efficient. And Edison knew it. But... Edison was earning nice sums from his direct current power plants, which he had a few patents for (really a monopol), and he didn't want Tesla to fiddle with his money. So...
At West Orange, New Jersey, Edison and his men began paying schoolboys to kidnap small animals off the streets. Edison used them in live demonstrations about the dangers of AC. He would have the small animal tied to a large metal slab, and electrocuted in deliberately crude experiments. There were posters up all around the city that said, "Warning!" at the top and in smaller print went on to warn residents about being "Westinghoused," as electrocution was called by Edison's men.
So really, Edison was not a very straight person.
Tesla was humilated by him, and because of him, Tesla's genious was not recognized by the public.
But at the end, the "good guys" won, and the fact is today, thanks to Tesla, we use AC, and it saves the electrical companies milliards of dollars every year!