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Can a neutral atom be affected by magnetic field?

  1. May 21, 2013 #1
    If we have a moving, neutral atom, say hydrogen, will it react to a magnetic field?
    If yes, why?
    If you ask why not, I argue that the atom as a whole is a chargeless entity.
  2. jcsd
  3. May 21, 2013 #2
    Yes. A group of charged particles with zero net charge can still have non-zero magnetic moments. The particles may have orbital angular momentum (such as the electron in hydrogen) or intrinsic spin, and these can all interact with magnetic fields.
  4. May 24, 2013 #3
    So, if the atom had a zero net magnetic moment, then it wouldn't be affected right? And is such an atom possible?
  5. May 24, 2013 #4

    Yes. un-ionized, unexcited Helium-4 has no magnetic moment: its electrons are both in the s-orbital (so no angular momentum) and the two electrons, two protons, and two neutrons are all respectively anti-parallel, so there is no total magnetic moment due to spin.
  6. May 24, 2013 #5


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  7. May 24, 2013 #6


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    Even Helium will show diamagnetic behaviour in a magnetic field so it will be influenced.
  8. May 24, 2013 #7


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    Think Iron.
  9. May 24, 2013 #8


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    An external magnetic field will 'affect' the absorption lines of many neutral atoms. See Zeeman Effect.
  10. May 24, 2013 #9
    What about Lorentz force, on a moving neutral atom?
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