Nikola Tesla Books
HIGH FREQUENCY APPARATUS the terminals of an alternating current generator having four field poles and having its armature or "rotor" driven at 1800 R. P. M. This machine would be termed a 60-cycle alternator because the current it delivers would make 60 complete cycles or 120 alternations in a space of one second. With reference to Fig. 1, let us assume that A represents the current as it starts from one collector ring of the machine. Following the direction indicated by the arrow, we find the current rises in voltage until it reaches its peak at B. The value then falls back to zero as the current returns to the other collector ring, C. At this point the arma0. maximum potential zero potential to sec maximum potential Fig. 1.-Diagram showing how an alternating current periodically reverses its direction of flow ture or rotor of the machine passes to the next set of field or stator poles and the current starts out over its circuit again, but in the reverse direction. For convenience, this is shown as below the zero line in the illustration. Leaving C, the current rises to the maximum at D and then returns to E. The period of time taken in the passage from A to E is just 1/60 second; in this space of time the current has made a complete cycle of two alterations, one in a positive
