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S_Wildjocks

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**Summary:**Considering a charged particle moving through a magnetic field, what forces does the particle exert on the magnet that is causing it to deflect?

Hi all,

probably a dumb question, but what force(s) does a charged particle exert on a magnet as it passes through it's magnetic field and deflects off?

For example, if I have a charged particle, moving at some velocity, and it is deflected through 90deg due to the presence of a magnetic field, what forces does the particle exert on the magnet?

Probably the best way of imagining what I'm asking is to imagine a charged particle traveling through space, and which passes by a bar magnet (which is aligned so that the particle deflects around it) which is also floating in space. What force is exerted on each?

I'm guess that the particle exerts an equal but opposite force to the force due to the magnet and which is exerted on it (F=qv×B=qvBsinθ), however, surely the mass of the particle matters too right? So if I were to look at it in a purely classical sense it would be F=mv^2/r... the radius of deflection will obviously be dependent on the field strength, particle velocity & mass, etc. But what equation should I use?

Which is it? Is it both?... I suspect that neither will give me the correct answer. I'm sure I'm missing lots here, some version on the Lorentz equation?

Thanks in advance.