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Sorry if I get some terminologies wrong I am not a physics major :)

If I had a big wind tunnel on earth blowing wind through a strong magnetic field (so the opposite poles of 2 giant magnets creating a giant magnetic field & the wind is blowing perpendicular to the magnetic field).

How would the wind force effect the magnetic field/would it? As well as does the gravitational force effect the magnetic field?

From my intuition, if I turn the wind tunnel off and just have the two magnets on and put a magnetic object in the middle, it would levitate in the field & would stay relatively stable in there. But as soon as I turn the air tunnel on I would think the object would be effected by the wind force and may start moving.

Does the wind actually move the magnetic field or is it just interacting with the object and the magnetic field is unaffected? Why or why not does the magnetic force not interact with the physical wind force?

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    $\begingroup$ It gets way more interesting if the fluid passing through the magnetic field is an electrical conductor: en.wikipedia.org/wiki/Magnetohydrodynamics $\endgroup$
    – Solomon Slow
    Commented Jul 21, 2022 at 15:27
  • $\begingroup$ That is cool! :) $\endgroup$
    – Jemima
    Commented Jul 21, 2022 at 15:29

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Magnetic fields exert a force on charged objects and magnetic objects. Air is usually neither.

If a charged particle moves in a magnetic field it experiences a force proportional to the charge, field strength and its velocity at right angles to its motion, $\mathbf{F}=q \mathbf{v}\times \mathbf{B}$. But uncharged air will not experience anything ($q=0$).

A piece of iron or a magnet will be attracted to the magnetic poles, with a force proportional to the field strength and the magnetic moment of the object. It will not hang in equilibrium due to Earnshaw's theorem: those toys with levitating magnetic objects do it by changing the field or using rotation. Were the wind tunnel active it would presumably accelerate towards the magnet but either be blown away or resist it, getting stuck to the wall.

There is a microscopic quibble here: oxygen and nitrogen molecules have slightly different magnetic susceptibilities, so there will be attraction towards the poles for the paramagnetic oxygen and a slight repulsion by the diamagnetic nitrogen. This effect is pretty microscopic, and if the wind tunnel is running the air will just mix.

In short, the magnetic field and the air will not interact: you cannot blow away the field. Had the air been a plasma it would indeed have trapped magnetic field lines and started to move them, producing complicated magnetohydrodynamic turbulence.

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  • $\begingroup$ Thank you Anders! :) $\endgroup$
    – Jemima
    Commented Jul 21, 2022 at 15:29

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