Before I became interested in E-bikes, electricity was still a fascination, especially after I read the book "Draw the lightning down" http://www.amazon.com/Draw-Lightning-Do ... 0520248295
Its from the quote "Destiny will draw the lightning down from heaven".
An atom has a number of electrons spinning around its core. The ideal state of copper has 29. An "Ion" is a named atom with an extra electron or one less than ideal. From this we can see that an electron or two can be pulled out of, or shoved into the orbits around the nucleus. If an ion gets too many electrons, it wants to electro-magnetically throw some of them away at the first opportunity, and if it has too few, it becomes increasingly "hungry" to steal one from its neighbors.
There are linear alternators. NASA Stirling engines use an example of this. A magnet slides back and forth in a straight line while hovering next to a line of copper wire. Electrons are are pulled/pushed at first in one direction, and then in the other. Its a simple way to make alternating current.
Now suppose you have plenty of room and weight is not an issue, like a large dam that water flows through. The downward-flowing water spins a turbine, which spins a shaft. Simple, powerful, and reliable. Engineers have determined it much more productive to have the generating magnets constantly spinning in one direction next to a coil of wire.
DC is good for short distances, and as the distances increase, there is too much waste heat, and the thick wires that would be required would be bulky and expensive. DC is simple, wonderful, and intuitive, but AC was a counter-intuitive flash of genius from Tesla.
I like to imagine that electrons are not created in one place and consumed in another, but that spinning magnets induce a chain of events along a wire, each copper atom receiving an electron shoved into it, and then almost immediately throwing one at it neighbor on the other side (whether that atom wants another electron or not)....and then...the direction of flow reversing 60 times a second (when using house current).
It must be exhausting. An unmeasurable number of jugglers in an incredibly long row, each managing 29 balls in the air, and one or two of those balls gets sent down the line to every single juggler...the event forced by spinning magnets at one end of the chain, all being performed almost instantaneously, near the speed of light (you'd need a vacuum and zero degrees Kelvin to get top-speed, but...it's fast enough right now for what we want, as it is).