Planck radiation law: The law which explained blackbody radiation better than its precursor, therefore resolving the ultraviolet catastrophe. This is based on the supposition that electromagnetic radiation is quantized.
For a blackbody at thermodynamic temperature T, the radiance R over a range of frequencies between the nu and nu + dnu is specified by:
R = 2 pi h nu3/[c3 [exp (h nu/k T) - 1]].