In classical electromagnetism, the magnetic dipole moment of an orbital electron changes when an external magnetic field is set up normal to the plane of the electron's orbit.
It is usually assumed that the radius of orbit remains constant, and the speed changes.
Can someone explain the reason behind this? Also, how does one explain the increase in the kinetic energy, considering the magnetic field does no work?

If we consider that both radius and speed change, then we could say that the decrease in electrostatic potential energy balances the increase in kinetic energy. Is this logic correct?

Note: I'm an undergrad. If you could answer keeping that in mind, (or share appropriate resources with them), I'd really appreciate it!


1 Answer 1


There is nothing that orbits the nucleus. The electrons are distributed around the nucleus in some regions. And the electrons are in equilibrium due to their magnetic dipoles.

Under the influence of an external magnetic field, the magnetic dipoles are turned in the direction of the external field. But the inner-atomic bonds are powerful and after switching off the external magnetic field, most materials return to their previous state of equilibrium.


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