Copper's Surprising Reaction to Strong Magnets | Force Field Motion Dampening

[Music] [Music] in this video I will be exploring magnetic braking and levitation utilizing the inductance of large copper plates these plates I picked up on eBay for a pretty reasonable price along with some very strong neodymium magnets together they behave in strange ways copper is not magnetic so they don't exactly attract each other but at the same time this magnet doesn't seem to want to slip off very quickly it drags across the plate slowly like it's moving through a thick fluid it's even more interesting if I drop the magnet on the plate it slows down midair and gently floats to the surface so if the copper is not magnetic something else must be causing this and many of you probably already know the answer has to do with electricity when a magnetic field moves through copper and many other metals it causes electrons to reorganize themselves and flow in a circular pattern perpendicular to the oncoming magnetic field of course the electrons were perfectly happy being where they were before the magnet tried moving them around and so they resist this movement by generating a temporary magnetic field of their own there's no attraction or repulsion just resistance to change one way that we can prove this resistance is due to the flow of electricity is by replacing the copper plates with a copper coil this coil of wire is not connected at the ends and so it does not form a complete electrical circuit if we tried to make electrons flow around this coil they would have nowhere to go and we can tell this is the case because when I drop a magnet through the center there is no resistance it falls through the coil as if it were not even there no slowing down at all if the resistance to movement we saw with the copper plate wasn't parent property of copper nothing to do with electricity the magnet should still slow down even with a disconnected circuit when I do connect the two ends of the copper wire now the magnet pauses as soon as it reaches the coil and it takes a moment to make it all the way through electrons can now make a complete orbit around the coil in response to the oncoming magnetic field and so the magnet slows down as its momentum is converted into electrical current if I once again disconnect the coil and bridge the circuit with an LED we can see a better indication of the electricity the LED is very efficient so powering it doesn't slow down the magnet quite as much as when the circuit was closed directly this is a simplified model of how the majority of the world's electricity is generated there are many different types of power plants but most of them are just trying to figure out different ways to more efficiently move magnets through coils of wire now back to the copper plates we can't so easily get electricity from these like we can from a coil but the electrons are still flowing and cause very heavy resistance to a strong magnet because of this we can do some interesting things like manually levitate a magnet above the surface I'm doing this by holding a second magnet underneath the plate it's not easy to make a magnet float in this way but it is fun to practice I found that using a very wide magnet on top and a smaller magnet underneath is the most controllable setup I made a small stand to hold my copper plates out of wood and acrylic glass the resistance to movement caused by the electrical inductance in the copper is the only reason this levitation is possible on a surface without this property a magnet will fly right off the side as soon as you try to lift it with a second magnet despite the resistance that we've seen to change magnetic fields pass right through copper as if it were not even there as we can see by how I'm able to rotate this small cube magnet from a long distance away even with the copper plate separating the magnet in my hand replacing the disc magnet with this smaller cube in the earlier setup allows me to walk it across the surface like a little robot and the motion damping provided by the copper gives me very precise control besides the generation of electricity there are a few other practical applications for this sort of motion damping high-speed trains and even some roller coasters use a magnetic braking system set up in a way very similar to this with powerful magnets usually electromagnets elevated above a conductive surface the magnets slow the vehicle down quickly without any surface to surface friction that causes damage in conventional braking systems between brake pads and rotors my favorite tabletop demonstration of magnetic braking is to swing a magnet toward a chunk of copper like a wrecking ball the magnet loses all of its momentum at the very last moment in a way that almost looks supernatural it reminds me of a scene in the second Matrix movie where neo stops bullets in midair what's really happening is of course the same thing that has happened in my other examples the magnets momentum is slowed by opposing magnetic fields generated by the flow of electrons in the copper and since the electrical energy isn't being collected by a circuit for any useful purpose it dissipates into the lump of copper as heat so the copper actually gets warmer every time I swing the magnet toward it but by is such a small amount that measuring the change would be very difficult all of the things that you've seen demonstrated in this video are described by two scientific principles Faraday's law of induction and Lenz's law so if you'd like to learn in more detail than what I was able to demonstrate here you should read up on those laws and I'll put links in the video description below for you to do just that now since you've found yourself watching this video presumably you enjoy learning like this learning about science and the world around us and so I know you'll enjoy my sponsor for this video brilliant org brilliant is an educational website that offers a large series of progressive courses through various subjects that allow you to learn in a really engaging way when they offer courses on physics of the everyday astronomy and logic and puzzles that's one of my favorite courses that I've been working through myself that allows you to work through lots of diff logical puzzles that keeps your mind engaged and gets you in the mood for learning it really helps you to learn in a lot of other subjects to be engaged with puzzles and logic because it just keeps your mind active and allows you to figure out various problems this can also be a great complement for school courses and textbooks if you're trying to learn say about mathematics you can go through brilliants course which allows you to do it in a really fun way as a great complement to your paper textbook this will help you learn a lot faster and in a way that you will remember because you've had fun doing it so check out brilliant org and if you do go through the link in my video description below so that they know I sent you and the first 200 people will get a special offer through brilliant so do it quickly if you'd like to check them out so you can get that offer I hope you've enjoyed this video I want to thank you for watching and please leave me comments below I would love to hear from you I'd love to hear your ideas for future projects and feedback on this video I still read all my comments and I love hearing from you so thank you for watching I'll see you next time

Channel: NightHawkInLight

Views: 5,502,650

Rating: 4.9233937 out of 5

Keywords: Magnets, Copper, Magnetic, Electricity, Induction, Faraday, Lenz, Edison, Generator, Levitation, Levitate, Float, Magnet, Braking, Magnetic Braking, Damping, NightHawkInLight

Id: sENgdSF8ppA

Length: 7min 46sec (466 seconds)

Published: Fri Jan 26 2018

Reddit Comments

[u/Meih_Notyou]

Holy shit, that part where he used the magnet/copper as a brake was so cool.

[u/WildebeestWizard]

This might be a bad place to try and get a science answer, but I'm giving it a shot anyway: Why does the coil need to be connected at the ends? The coil itself clearly is windeded up so closely, that wires are connecting all over? Wouldn't this allow for a (or, rather, several) possible circuits to made?

[u/niconpat]

No mention of Eddy currents?

Lenz's law and Faraday's law of induction are fundamental to what's happening, but this video is demonstrating Eddy currents without mentioning Eddy currents.

[u/catsandicecream]

bullshit, this isnt about law enforcement officers from the 40s at all.

[u/LastTrainLongGone]

Came for the copper, stayed for the parrot

[u/MIchaelangelo_paints]

Thank you for posting. really interesting

[u/Colonel_Planet]

@4:04 i physically recoiled in fear.

PSA: DO NOT HOLD SMALL NEODYMIUM MAGNETS IN YOUR HAND NEAR LARGER ONES IN MOTION

that shit will literally guillotine part of your finger off when it clamps to each other at lightspeed and the only thing in the way is a tiny bit of your finger skin

[u/Bon_Qui_Qui]

That’s amazing. I understand chemistry easily, but electricity and magnets I just can’t grasp. Might as well be magic.

[u/TheRabidDeer]

"and many of you probably already know the answer to this..."

Oh, yeah... totally do.

...

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