摘要：The Bohr-Sommerfeld quantum theory specifies the rules of quantization for circular and elliptical orbits for a one-electron hydrogen atom-like system. This article illustrates how a formula connecting the principal quantum number 'n' and the length of the major axis of an elliptical orbit may be arrived at starting from the quantum mechanical description and how, in the limit when 'n' is large, one gets the expected classical result.
