Photoelectric problem

[silverek]

The wavelength of visible light is between 400nm and 760nm. We shed a 100W visible light on a piece of metal.

In classical electrodynamics, what is the number of electrons escaping from the Lithium surface per second, if the metal absorbs 20% of the light? Lithium has a work function of 2.38eV.

[Gokul43201]

What minimum wavelength will lead to photoelectron emission (determine this from the work function) ? Now assume that the visible light has a flat frequency distribution and determine the number of sufficiently energetic photons incident on the metal (from the relevant fraction of total power). 20% of this number of photons may be assumed to each produce one photoelectron.