Atomic polarizabilities: Quantal and classical perspectives

The mechanism by which an external electric field induces in an atom an electric dipole moment is discussed from classical and quantal points of view. It is shown that the expressions for the atomic polarizability ct derived from each of these viewpoints are, to the same level of approximation, identical. The classical perspective is, however, more intuitive and provides a more insightful picture. The presentation is at the undergraduate level. (C) 1997 American Association of Physics Teachers.