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As a first example and to introduce the Magnetization vector (

**M**), my textbook shows a ferromagnetic substance in a uniform magnetic field (

**B**).

Then, every atom of the substance is oversimplified as a single electron moving in a circle, having its own magnetic moment (

**m**) macroscopically being zero because of thermic agitation when no

**B**is applied. When we apply said

**B**, all those

**m**s will point averagely in one direction, creating a macroscopic magnetic moment

**m**≠0.

_{tot}My question is:

when no

**B**is applied, a single atom of the ferromagnetic substance will still move in a circle (which I know is a simplification) and will have a centripetal acceleration (

**a**) with magnitude a

_{c}_{c}= v

^{2}/R, with

**R**being the radius of such a circumference and

**v**the speed of the electron.

If we now apply

**B**properly, the Lorentz force should act on the electron in such a way that

**a**increases, and I assume that for this reason also

_{c}**v**increases.

But if

**v**increases then it varies with time in such a way that causes the Lorentz force to increase, leading to an indefinite loop that causes the speed to diverge to infinity.

Can someone please explain what is wrong with this reason? Thank you in advance.