On 2020-12-06, Peter Wieck wrote:
Electricity in a wire, AC or DC, moves much faster than the "speed of light" - which is defined by its speed in a vacuum. Pop an electron into the system at one end, and that instant, one pops out at the other. The water that one puts in a pipe is not the same water that comes out the other end (unless the pipe was empty initially - not possible with electrons in a wire). With AC current, it is entirely possible that no individual electron makes it down the entire length of the wire.
I'm sorry, the first two statements are not true.
'c', the speed of light in a vacuum, is the speed limit for this universe,
and is only reached by massless particles such as photons. No signalling
happens faster than that.
Electrons have mass.
The signal velocity of photons in vacuum is 1.0 (* c).
The signal velocity of photons in most fiber optic cables is around 0.67.
The signal velocity of electricity in cables varies by the composition of
the cable and how it is made, but is typically between 0.58 and 0.78.
Peter is correct that the electrons or water you get out of one end of a pipe
are not the same electrons or water you put in. In a conductive metal, the
electrons are freely shared between neighboring atoms, and applying a voltage
at one end of a wire causes the electrons to jostle each other right on down
the line.
Wikipedia's article
https://en.wikipedia.org/wiki/Speed_of_electricity
is pretty well written.
-dsr-