I'm not talking rock music here, I'm talking electrical currents – alternating current - AC, and direct current - DC, the two ways in which electricity flows.
It's also in the back, and it takes the alternating current that just came from the inverter and creates a rotating magnetic field that causes the motor to turn.
Alternating current means that the electricity flows to the load and back to the generator, to the load and back to the generator and the frequency that this happens is called cycles.
He and his colleagues at the ARLs Aberdeen proving ground in Maryland have developed a test in which they apply alternating currents of various frequencies across a plate Plates electrical properties.
Tesla's error, if it can be defined as such, is that he was simply ahead of his time in trying to propose alternating current as the better method of energy generation.
The people who were giving him money for the company didn't like his ideas about developing technology related to alternating current, so they fired him.