Lenz's Law with Copper Pipe (H16) [5K20.25]
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers and askers link it as the classic visual demonstration of Lenz's Law and eddy-current braking when discussing magnets falling through conducting tubes.
Recommended by 1 people across 1 different months, 2018 to 2019.
What it is
A short MIT physics demonstration in which a magnet is dropped down a copper pipe and falls much more slowly than it would in free air. The video explains that the falling magnet induces currents in the pipe, which by Lenz's Law create a field opposing the magnet's motion.
What people said
Recommends Michael Seifert · 2018-08 · Physics Stack Exchange · on “Why magnet do not feel force?”
The magnet does feel a force, as can be seen in this classic demonstration: Lenz's Law with Copper Pipe [this video] To see what's happening, think of the tube as a stack of loops. As the magnet moves towards one "loop", it induces a current, and by Lenz's Law, this loop of current acts like a magnet of the opposite polarity. Thus, the current exerts an upward force on the magnet. Equilibrium is reached when the magnet moves fast enough that the force from the tube exactly counteracts the force of gravity on the magnet; at that point, it falls at a constant velocity through the pipe, instead of accelerating downwards.
Cites rob · 2018-04 · Physics Stack Exchange · on “How much current is induced by a free falling magnet?”
For a stack of coils, as you say, this is actually a famous result, but not quite in the way that you've phrased it. If you drop a magnet through the air from some height $h$, it'll generally hit the ground with a speed $v$ that obeys $\frac12 mv^2 = mgh$ --- that its, its gravitational potential energy gets converted into kinetic energy. However if you drop a magnet through a conducting pipe [this video] , or through a series of conducting rings as you suggest, it'll strike the ground with a much smaller kinetic energy: instead of being converted entirely into kinetic energy of the magnet, some of the magnet's inital gravitational potential energy is converted to electrical energy in the conduct
Cites user238989 · 2019-08 · Physics Stack Exchange · on “Experiment: Magnet falling in a copper/aluminum pipe”
We know that when we release a magnet in conducting pipe (aluminum, copper, etc..) it will be subjected to a magnetic force induced by the induced current. This magnetic field will be created in a manner opposite to the rate change of flux caused by the falling magnet. This in turn will slow down the magnet as you can see here [this video] . I have seen on this forum [LINK] message #6, the equation of the terminal velocity reached by the magnet during the fall where $v$ is the terminal velocity, $m$ is the mass of the magnet, $g$ is gravitational acceleration, $\rho$ is the resistivity of the tube, $R$ is the inner diameter (I am not sure why it is symbolized by R), $B$ is the magnetic flux densi