That is where things get even more complicated and the atomic structure of conductors come into play. The EM waves can propagate at typically light speed, or just under, but the electron's have a
velocity we call the electron drift that is actually much much slower.


(in a way it's analogous to how slowly a magnet falls through the copper pipe demonstration)

Tau has no bearing on whether current can/will flow or not. The effect it has is how "curvy" the rise of current is, relative to the timing of your test. With an infinite tau, the curve is going to be a straight line, not only because the time is infinite, but also because the beginning part of the curve is almost straight anyway.

The magnet slowing through a copper pipe is a demonstration of Lenz Law due to the fact that copper can be diamagnetic. Electrons move at the speed of light...you can limit the number of them moving through a circuit but not slow them down.

Bill

No
It's because the shorted single turn copper coil is producing a magnetic field that apposes that which created it.


Brad

lol basically, I have no doubt both of you understand Lenz Law. The term Diamagnetic
can be confusing though and I'm not even sure as to whether that's a 'proper' way to
say it although I perfectly understand what you mean because the copper essentially
does become 'diamagnetic' as far as I can tell. seems like the same explanation.
However I also thought diamagnetic materials referred more to materials that naturally
exhibit a strong diamagnetism, much more so than what may be found in normal conductors like
copper. For example Bismuth. still, confusing.

hell it's been a while myself, I'd have to look up 'paramagnetic' but i'd imagine it's the opposite effect.
I'm pretty sure Bismuth is diamagnetic though. It would certainly seem counter intuitive to say
that copper is not diamagnetic when it does seem to behave that way, like aluminum. I have
never heard that word used to describe the Lenz effect however which is why I can imagine
there is some scientific separation. I'm not one to nitpick over terminology as long as I can understand you of course, but if there IS some separation in the physical explanation of Lenz
law and diamagnetism then I suppose Brad would be correct in excluding the word Diamagnetic.
I suppose the difference lies in the changing magnetic field vs a non changing. Bismuth requires no lenz interaction to get the opposition.  (at least from the newtonian side of things to the quantum side of things lol)



edit- ok so copper and aluminum are diamagnetic like many other metals. However their
naturally occurring diamagnetism is quite negligible when compared to Bismuth.
So you could say, yes, the magnet acts the way it does in the pipe because copper is a diamagnetic. But to give that explanation also requires that we explain the diamagnetic interaction between the magnet and the copper is a direct result of the Lenz effect, the opposing fields.
so long as a changing magnetic field is brought into the explanation it seems totally proper.

It only becomes confusing when someone can think that copper is naturally diamagnetic like
Bismuth and will yield that field opposition without any changing field interacting with it.

If the pipe is cooled down enough,so as it became superconductive,would the magnet still fall?

Think about that,and how it relates to the ideal coil,which is also made of many superconductive loops.


Brad