Comment on ‘‘The strange polarization of the classical atom’’ [Am. J. Phys. 55, 906 (1987)]

There has been much interest recently, both experimentally and theoretically, in ‘‘Rydberg atoms’’—atoms with large principal quantum number n. A classical treatment of the associated Coulomb field problem describes most of the features of these atoms. Using classical mechanics, Solem¹ recently showed the existence of an interesting, counterintuitive effect for an atom in a weak uniform electric field: The response of the electron was orthogonal to the direction of the applied field. This effect was shown both analytically by the method of variation of parameters and numerically by direct integration of the equations of motion. Such a basic effect in a simple system should, however, admit an elementary derivation. This we provide here.