  Using Pearson correlation coefficient a statistical analysis of Duane-Hunt
and Kulenkampff's measurement results was performed. This analysis reveals that
empirically based Duane-Hunt's law is not entirely consistent with the
measurement data. The author has theoretically found the action of
electromagnetic oscillators, which corresponds to Planck's constant, and also
has found an alternative law based on the classical theory. Using the same
statistical method, this alternative law is likewise tested, and it is proved
that the alternative law is completely in accordance with the measurements. The
alternative law gives a relativistic expression for the energy of
electromagnetic wave emitted or absorbed by atoms and proves that the
empirically derived Planck-Einstein's expression is only valid for relatively
low frequencies. Wave equation, which is similar to the Schr\"odinger equation,
and wavelength of the standing electromagnetic wave are also established by the
author's analysis. For a relatively low energy this wavelength becomes equal to
the de Broglie wavelength. Without any quantum conditions, the author made a
formula similar to the Rydberg's formula, which can be applied to the all known
atoms, neutrons and some hyperons.
