Abstract: The study of blackbody radiation has not only promoted the development of thermodynamics but also directly led to the emergence of quantum mechanics. A blackbody at a temperature above absolute zero can radiate electromagnetic waves. For electromagnetic waves, the product of frequency (ν) and wavelength (λ) equals the speed of light c. Wiens displacement law states that the product of the peak wavelength of blackbody radiation and temperature equals Wiens constant. However, deriving from Plancks blackbody radiation law reveals that the product of the peak frequency and peak wavelength is approximately 0.568 times the speed of light, not c. To address this counterintuitive result, we examine the differences and connections between the definitions of blackbody radiation power expressed in terms of frequency and wavelength, thereby elucidating this counterintuitive issue.

Key words: blackbody radiation, electromagnetic waves, Wiens displacement law