This lecture covers sections 1-2 and 1-3 of McQuarrie:
A blackbody is a source of radiation whose spectral emission depends solely on the temperature. Classical physics cannot explain the blackbody's spectrum. Max Planck was able to account for the spectrum using the assumption that the energy levels of the oscillators responsible the radiation was quantized.
The real beauty of the Planck blackbody radiation law is that it provides an explanation of the spectrum (a macroscopic property) based on an understanding of the physics at a microscopic level. Moreover, the theory has only one new parameter. This parameter, h, is now held to be one of nature's universal physical constants.
Another satisfying aspect of the Planck law is that it encompasses other known, experimentally determined aspects of blackbody radiation: (a) the Wien displacement law and (b) the Stefan-Boltzmann law. In each case, the equations are derivable from the Planck law and the empirical constants are rationalized in terms of more fundamental constants.
Click here to view a copy of the M-file for this Lecture. This m file and all of the others have line breaks missing. Do not "save" the file. Instead, highlight the entire text and copy and paste it into the MATLAB editor (select a new M file in the File menu of MATLAB first). Now the script will have line breaks and you can do a " save as" to save it as a named file.