A Contemporary Analysis of Blackbody Radiation: Proving the Limitations of Classical Theory Using Accessible Instrumentation

This paper investigates the theories surrounding the phenomenon of blackbody radiation, specifically the Rayleigh-Jeans approximation and the Planck law. Using qualitative and quantitative experimentation with graphite rods as a blackbody, the Rayleigh-Jeans approximation is analyzed for its validity. After graphical analyses of graphite rods under varying temperatures, the Rayleigh-Jeans approximation held up for extremely large wavelengths but did not hold up for smaller ones, proving to be an inaccurate model for predicting the nature of a blackbody. Instead, it was found that the Planck law aligned with experimental data, assuming that energy is emitted in discrete multiples of a quantity known as a quanta instead of in a continuous spectrum. Not only did this lead to the conclusion that the Planck law was a more valid theory describing the phenomenon of blackbody radiation, but we also observed, by extension, evidence of Wien’s displacement law and the Stefan-Boltzmann law.