Re: Explain how Lynn's Law works.

Good question, and usually only covered in college.  First, it's called 
Lenz's Law, and it is a variant on the well known law "Nature always 
fights back".  How it works:  when you drop the magnet down the Cu or Al 
pipe, the moving field generates what are called "eddy currents" in the 
pipe metal.  Now you have a current through a conductor which generates a 
magnetic field.  Then this *induced* magnetic field (induced by the motion 
of the magnet through the pipe OPPOSES the magnetic field generated by the 
permanent magnet, which reduces the net acceleration that the magnet sees 
while falling, which slows the magnet down.  The stronger the magnet or 
the greater the conductivity of the pipe, the stronger the deceleration 
effect.  If you should use a PVC pipe, you will see no effect at all (the 
magnet will move at full speed) since you can't induce any current in a 
non-conductor.