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

To read more about Lenz & Faraday's Laws see the following links:

Thanks for watching!

[MilanKarakas]

At 1:37, you said "...there is no attraction, nor repulsion...". Wrong. There is attraction or repulsion, depending whether magnet goes toward copper clad or away. Copper is good conductor and magnet generates eddy current, which in turn produce exactly 'mirrored' magnetic field when magnet approaches the surface of the copper. When magnet going away from the copper, you can feel resistance because then magnetic field 'flip'. Still somewhat 'mirrored', but as a 'negative', or in reverse. When magnet going toward copper, north produces eddy current that produces north pole in copper. When you pull magnet from the surface, north pole produces south pole - which attract or as you said - make a feeling of the resistance. When stationary, no eddy current.

[OfficialMaxBox]

So nice to have the video immediately start with the good stuff.

[PineappleForScale]

Every physics related thing is fascinating utill it is added to our syllabus.

[rogerbeck]

I’m 69 and that’s the first time I saw a magnet interacting with copper in that way. Very interesting, and thanks to you.

[caveofskarzs]

As other people have said, this also works with aluminum. I have seen magnetic brakes used on a land speed record car that had aluminum wheels, not meant to slow the car from top speed, but to slow it down once the parachutes have been used. It was very ingenious. They had a ring of neodymium magnets on a hydraulically controlled plate.

[roybunnell]

I am a retired engineer and science teacher, and thoroughly enjoyed your demonstrations. I had never seen the magnet-copper wire coil demo before, and it is a great

[GhostOfJulesVerne]

I just tried this at home and it feels like I'm dragging the magnet through molasses. Super cool!

[frankhartranft]

Great film. I'm sharing it with my 7-year-old grandson, who spontaneously shared his interest in the subjects of magnetism and electricity.

[jmcsquared]

2:21 I have never thought to have my students actually connect an open inductor like that before! I also love how you used an led to show the emf generation. I tried it with a small regular bulb but it was no use; the emf generated seems to be only around the hundred mV range. So, I definitely need to buy some small leds - and flat copper plates !

[matthewtalbot-paine]

I think I've just found a way to make my toilet seat shut quietly

[MrCharlieCom]

I used to repair aircraft gyro instruments. Some types of gyro instruments use magnetic damping to dampen gyro gimbal oscillations. Also, some bait-casting fishing reels use magnetic damping to control backlash.

[wimwiddershins]

Superb demonstrations. Prior to this I'd only observed the effect using a Cu tube and small magnet dropped through. These are far more visually interesting.

[Gunbudder]

i was just thinking about this video, and i think its possible to polish the surface of steel using magnetic breaking. the traveling fair where i live has a ride that takes you up about 100 feet on a tower and drops you. The way the ride stops is electromagnetic breaks that fit around metal fins. from what i remember, there were 4 metal fins that were at least a foot long and probably 8 inches wide. likely, they were bigger as they were far up on the ride. the part of the ride with the seats that falls rides on a square piece of scaffold with wheels to keep it aligned, and it has 8 electro magnets, one for each side of the fin. the fins are attached to the outter framework of the ride, so force applied to the fins sits on cement pads placed on the ground. the failsafe is a massive pile of recycled tires under the seats. if the magnetic breaking fails, you literally just land on a huge pile of rubber.

The interesting thing to me is that the fins were POLISHED. They stood out as extremely polished to a perfect mirror finish, and the polished part of the fins was only where the breaks run over them. It has always made me wonder if some kind of surface stripping happens when you are breaking such a massive load over a fairly short distance. also it freaked me out that the ride didn't use permanent magnets and only have a pile of tires as a failsafe.

[TheBuffaloPaladin]

I was not a great physics or chemistry student, despite enjoying both principles. This lesson would’ve gotten me excited about learning.

[MyRadDesign]

Laser levels use this to dampen unwanted vibrations. A copper disk is mounted at the bottom of a pendulum that is free to pivot. A magnet is mounted below the copper disk and causes the laser to self level rapidly and be resistant to small vibrations applied to the mount. In this application the magnet is stationary to avoid magnetic fields including that of the earth from effecting the accuracy of the laser level. Without the magnet, the laser would eventually self level, but would be too sensitive to vibrations to be useful in most construction environments.

[dantefaulk]

No way! That"s awesome! I've known about these principals for a long time but never seen it demonstrated this well. 10/10! great job Ben! Also, maybe put some links in the description for the magnets and the copper plates? Thanks!

[bmello]

Electrical theory is every single day at my job so this principle is nowhere near new but it is cool to see how others explain things and compare them to how I describe principles to newer folks to the trade. Excellent video my friend

[thermophile]

I already knew a little about this, (not much) but you expanded my knowledge in a way that was both easy to understand, interesting, and visually stunning.

[rogerwhittle]

I was an MRI Field Engineer before I retired and we often had fun with the Lenz effect. When MRI's were quite rare, there was always a drawer full of 1" steel washers on bits of string, so that visitors could 'see' the strength of the magnet. We soon got fed up with having to partially dismantle the brutes to get these out when, inevitably, some muppet dropped their washer and it vanished into the bore. We found a spectacular way of demonstrating the strength of the field, safely, by use of aluminium plates, about a foot long, eight inches wide and as thick as we could find - usually about 4mm. (Sorry to mix standards, but that is perfectly logical to me!)


When the user had a bunch of students or sometimes newbie doctors and we were on the premises, they would always ask us to "...do the trick..." Having first demonstrated that aluminium is not magnetic in any way, you place the plate upright on its short dimension, on the end of the patient table furthest from the bore of the magnet. Then you ask them what would happen if I let go. They all look round, because it's a trick question, right? It''l fall over.


Of course, as soon as you let go, it falls over and they all look relieved. Then you move the plate as close as you can to the mouth of the bore (disguising the fact that you can feel the Lenz effect working against you.) The you ask, what will happen now, given that it is non magnetic? They look at each other again, this time not so sure, but 99 times out of a hundred they've never heard of the Lenz effect and 'shorted turns'. When you let go and it barely moves (sometimes you have to give it a bit of a shove to get it moving) they are astonished and mystified in equal measure. It falls very, very slowly, although it does accelerate slightly. It's a great trick and a whole lot more spectacular ( and safer) than the old steel washers!

[DrakiniteOfficial]

Everything in this video was amazing, but the part that surprised me the most was the bit where you rotated that cube from like 2 feet away. That's the farthest distance I've ever seen *tangible* magnetic effects (aside from compasses), considering that usually, magnets only overcome friction when they're a few inches apart.