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Neutral atom

  1. Apr 8, 2010 #1

    People all know that a neutral atom has no net charge.

    Well, does that mean that it neither creates an electric field nor is affected by any electric field?

    I wonder whether it's correct or not, because the distance between a test charge outside this atom is closer to its electrons relative to its protons.

  2. jcsd
  3. Apr 8, 2010 #2


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    There are two aspects to answering your question. The first is classical, and the second is quantum mechanical, or if you prefer, chemistry.

    1. Tackle this using classical E&M. Put a charge Q at an origin. Now, on a spherical shell at a radius R, put an amount of charge -Q that is spherically symmetric about the origin.

    Using Gauss's Law, what is the E field at a field point r>R?

    2. An electric field doesn't affect an atom in ways that it changes its path or anything similar to a charged particle. However, it can change it internal "structure", such as its energy levels. The Stark effect is one clear example. At some point, with sufficiently high E field one can also induce an electric dipole by shifting the orbital geometry with respect to the nucleus, etc. So yes, an electric field can affect a neutral atom, but not in the same way you may have in mind.

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