FTP, name this idea that in physics there is always some level at which nonclassical theory agrees with the classical.
It is demonstrated by the fact that when frequency is small, the size of individual quanta will be negligible.  If the h in Planck's constant equals 0, light will behave only as a wave and never as a particle collection.  Before its formulation, there were two radiation laws: one classical, and one for the Bohr model.  FTP, name this idea that in physics there is always some level at which nonclassical theory agrees with the classical.
It is demonstrated by the fact that when frequency is small, the size of individual quanta will be negligible.  
correspondence principle