The wave solution to the Photoelectric effect

Hi there.

I was recently examining the relationship between the work function of a material and its threshold wavelength. It was clear to me that the relationship is expressed as:

(λW)² = c/2

Where λ is the threshold wavelength, W is the work function, and c is the speed of light. However, I am unable to find the name of this solution online.

Does anyone know what this relationship is called, and a link that explains it?

Thanks in advance for your help.