EXPLAINED: Lenz’s Law (Copper Pipe Demo)

EXPLAINED: Lenz’s Law (Copper Pipe Demo)

Today I wanted to demonstrate a sciencey-type effect I find pretty cool which is based on the concept of
electromagnetic induction. So let’s get right to it. Now what I have here it is a copper pipe
any very strong neodymium magnet. The magnet right now is wrapped in
electrical tape because I learned very quickly that if you let two of these get too close together they will definitely attract one another
and slam together with a force such that they will begin to
break pieces off of one another if they do it too many times. So the tape just
serves to soften the blow if either one of them wonder to close the
other. Now copper is an electrically conductive metal which just means that
it facilitates the flowage of electricity but it is definitely not
magnetic. See? But something very interesting
does happen when you drop the magnet through the pipe. However I do need to preface this
demonstration by telling you this is just the regular copper pipe I got Home Depot, and this is just a regular neodymium magnet I got on Amazon. There is no tom foolery, schenanigans, or
wizardry involved. It’s just science. Alright check it, here we go.
Magnet… pipe… What?
Ok one more time. Okay, from the top. Again there was no tomfoolery involved.
Just science. Also, I like saying tomfoolery. So now on to the
explanation as to why the magnet falls so slowly through the pipe when neither one of them seems to be attracted
to the other. The reason for this seemingly strange behavior was
discovered in 1835 by Russian physicist named Heinrich Lenz. Lenz’s law says that an electric current
induced by changing magnetic field will flow such that it creates its own
magnetic field that opposes is the magnetic field that created. Duh… And so in terms of the pipe / magnet
demonstration what’s happening here is that as the
magnet moves through the pipe it induces an electric current in the
copper that moves through it. That electric current itself generates a magnetic field that opposes
the magnet as it falls. And if that doesn’t make much sense to
you then don’t worry, you’re in good company. Magnetism in general is a crazy
quantum-mechanical effect that’s been magnified so that we humans can perceive
it on a macroscopic scale. But it does make for some pretty good
demonstrations, I think.


  1. having the pleasure of studying magnetism at the moment. Not really has to be one over these subjects we'd love to skip.

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