The Invention

Thomas Alva Edison ( his crew of 16 researchers) invented the electric light bulb, using a carbon filament. He patented the idea and used existing technology ( the electric dynamo ) to send the electricity directly through and across the filament in a loop. This is called Direct current. It just went one way, and was not efficient and could not be transmitted any long distance.

Alternating current shifts back and forth using Faraday’s discovery that a magnetic field creates an electric field and an electric field creates a magnetic field.(1) Nicola Tesla had invented three parts to make his plan work. First, he created an AC power generator which used the forces of Faraday’s discovery to turn a metal loop through a magnetic field and thus turn the energy to mechanical energy. Next, he then invented two transformers.(2) One is a step up transformer. It converts the current to voltage by having less copper coils on one side of a horseshoe magnet than the other side coming out.(3) After the voltage is stepped up, the current (amps) is automatically stepped down due to Ohm’s Law which states that V= I x R , meaning there is an inverse relationship between current and voltage. Now, Tesla could carry the voltage great distances and at high amounts and then step it back down using the opposite process. This made long distance transmission possible. The wire carrying the voltage would not get too hot and then when he stepped it down, he could step it down to an exact amount (60Hz) which then could be the standard for appliances. This was accomplished by the Resistors (R ) in the equation. It would regulate how much current was getting through to an exact amount.(4)

 Why was the Alternating Current Invented?

At the time there was simply no way to transmit electricity safely or efficiently over long distances. The ability to transmit electricity over long distances would open rural America as a market for electrical devices, allowing the electrical devices being enjoyed by businesses and the wealthiest of Americans to be used by everyone.  Who ever could put in place a system of electrical infrastructure would be putting themselves in a position to dominate a huge portion of the market for electricity and electrical appliances .


1) Van Valkenburgh, Nooger & Neville. Basic Electricity. Edited by Alice J. Tripp. Indianapolis, Indiana: Sans Technical Publishing, 1992.

2)Tesla, Nicola. The Nikola Tesla Treasury. First. Bedford, VA: Wilder Publishing LLC, 2007.

3)Hewitt, Paul. Conceptual Physics: Alternating Current. May 22, 2011.

4) Valkenbrugh

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