There is iron in our blood, which is magnetic. Roughly how strong would a magnet have to be to induce a noticeable attraction? It would be nice to know this for several distances. Also, do electromagnets that strong exist?

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    $\begingroup$ Let me put it this way...you can buy tools made of copper-beryllium which is sufficiently a-magnetic that you can use them in a multiple Tesla field. Alas they are (1) muchos expensive and (2) soft enough that you have to use them carefully on steel parts. $\endgroup$ Oct 15, 2011 at 0:54
  • $\begingroup$ @DMckee, CuBe is rather hard. The comparision to steel is a problem, because the anglosaxon use of "steel" is inflationary. It covers rather soft to springhard alloys. The use of CuBe is often in applications where sparks (by chipping etc) are not acceptable. $\endgroup$
    – Georg
    Oct 15, 2011 at 10:42

2 Answers 2


Humans are weakly diamagnetic. Rather than being attracted by a magnetic field we would tend to repel the lines of force.

Look at the work of the High Field Magnet Laboratory http://www.ru.nl/HFML/, in particular http://www.ru.nl/hfml/research/levitation/diamagnetic/ where they demonstrate levitation of a living frog. It took about 16T to levitate the frog.

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    $\begingroup$ To clarify, this is not due to the small amount iron in our body, but rather due to the large amount of water. $\endgroup$ Oct 15, 2011 at 1:16
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    $\begingroup$ wrong, almost all components of a body is diamagnetic! Eg fat etc. This should be known better: Every substance is diamgnetic, only some are paramagnetic or ferromagnetic additionly, this two effects obscure the basic diamagnetism. $\endgroup$
    – Georg
    Oct 15, 2011 at 10:35
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    $\begingroup$ Hi Georg - I was referring to the initial questioner's "There is Iron in blood. Iron is magnetic" and pointing out that the effect from this is negligible. I do admit to a simplification :) We both agree that the iron in the body's heme complexes contributes nothing to its overall magnetism. $\endgroup$ Oct 17, 2011 at 19:24
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    $\begingroup$ The frog did not seem to be enjoying his levitation. ;-) $\endgroup$ Jun 22, 2016 at 2:22

Mainly the iron in the blood is incorporated with other components. In the blood, plasma may be those forces of attraction are a lot stronger than the forces of attraction between a magnet and a magnetic component. Well, if it comes to bonds, they are the strongest forces and I guess, that to have a magnet strong enough to attract a human, we will have to first break all the bonds between the haem and globin, and that's not easy at all

That is purely my guess!

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    $\begingroup$ -1 At high magnetic fields the paramagnetic and diamagnetic properties of atoms and molecules start to really matter. Iron in the blood is not the only thing that would be affected by the field. $\endgroup$ May 9, 2013 at 18:09

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