Levitating a magnet in a Bismuth bowl?

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I wonder if it would work to cast a thick-waled bowl of bismuth and drop a magnet into it, would not that levitate the magnet? I have seen other setups but they seems more complicated.
 
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  • #2
berkeman
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I wonder if it would work to cast a thick-waled bowl of bismuth and drop a magnet into it, would not that levitate the magnet? I have seen other setups but they seems more complicated.
Welcome to the PF. :smile:

Can you post a link to the article that made you think this was possible? Thanks.
 
  • #3
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@berkeman , I believe he is referring to the videos online that show levitation of a magnet between two plates of bismuth.

@rolnor, the problem is how this "levitation" in the videos is achieved. The actual lifting off the magnet actually happens with a strong magnet above or below, and the diamagnetic bismuth only serves to stabilize horizontally, and from flipping the small magnet around. If you dropped a magnet into a bismuth bowl, it would just lie at the bottom. If you put a strong magnet under the bowl, the small magnet would flip around and be even attracted to the bottom of the bowl.
 
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OK, I think I have seen example where a thin sheet of bismuth is levitated on topp of a magnet on youtube?
 
  • #5
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Yeah. The problem is that while bismuth, and even more so pyrolite graphite is diamagnetic, it is still very weakly so. So, the diamagnetism can levitate a paper-thin sheet of graphite, but for levitating a magnet on its own it is too weak. That's where the regular magnet comes into play, to do the heavy lifting, and the graphite or bismuth only corrects the very small horizontal forces.
 
  • #6
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Now I have a link to Youtube, I dont find the bismuth-link but I have a link with graphite;
 
  • #7
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Yeah. The problem is that while bismuth, and even more so pyrolite graphite is diamagnetic, it is still very weakly so. So, the diamagnetism can levitate a paper-thin sheet of graphite, but for levitating a magnet on its own it is too weak. That's where the regular magnet comes into play, to do the heavy lifting, and the graphite or bismuth only corrects the very small horizontal forces.
OK, so iron is very much stronger magnetic than the graphite or bismuth, iron is paramagnetic and the other two are diamagnetic. If bismuth was as strong diamagnetic as iron is paramagnetic maby my idee would work.
 
  • #8
nasu
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Iron at room temperature is ferromagnetic. If it were just paramagnetic, the effect would likely be comparable (as week as) for bismuth. Just with opposite sign - attraction and not repulsion.
 
  • #9
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OK, now its more clear, thanx.
 
  • #10
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Iron at room temperature is ferromagnetic. If it were just paramagnetic, the effect would likely be comparable (as week as) for bismuth. Just with opposite sign - attraction and not repulsion.
Is it possible to explaine the difference between these three without using a lot of quantum-math? I am an organic chemist and it was a long time since I read physics.
 
  • #11
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I have one more question; Would it be possible to make an alloy thas is more diamagnetic then bismuth or graphite? I compare with ferromagnets where it is possible.
 
  • #12
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The only known substance that is more diamagnetic that pyrolite graphite is a superconductor.

I think, and I'm going out on a limb here with my understanding, that non-superconducting diamagnetism mostly comes from electron spin being realigned. An electron's magnetic moment due to spin is just very small, there's not much to be done about it.
 
  • #13
nasu
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The spin magnetism is mostly responsible for ferromagnetism so it is not so negligible. Paramagnetism is also related to spin magnetic moment.
Diamagnetism is associated with the orbital magnetic moment.

However there are also mixed terms (spin-orbit) in the general treatment of the magnetic behavior so this separation is an (useful) simplification.
(see for example Van-Vleck paramagnetism).

Also, in a given material in general can be present both diamagnetic and paramagnetic contributions, from orbital motion and spin and the material will show the behavior of the strongest "contribution". For example, copper has one unpaired electron whose spin can be expected to "produce" paramagnetism. But the diamagnetic contribution of the closed shells is larger so overall copper (as a metal) is diamagnetic.
 

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