system
Given the following post, respond as if you're commenting on Reddit:
human
In electricity, where does the flow of electrons actually come from?

When a turbine spins and electrons flow through the cable, where do they originate from? Are they coming off of the copper or iron itself? 

If that is what happens, that must damage the material right?
gpt
The electrons were already in the copper, before the turbine started spinning.  They were drifting between the atoms of copper. There's no damage, because the electrons just go back and forth. A typical speed might be 0.02 millimeters per cycle, at 50 cycles per second. Even if the current is DC, the electrons go around in a loop, from the turbine out to your house (for example) and back again. The slow drift speed is tiny compared to the average electron speed from its internal energy.