1. The problem statement, all variables and given/known data A clean surface of potassium in a vacuum is irradiated with light of wavelength 5.5 x10 -7 m and electrons are found just to emerge, but when light of wavelength 5.0 x 10 -7 m is incident, electrons emerge with energy 3.62 x 10-20 J. Estimate a value for Planck's constant. I understand the basics like finding work functions and Einstein's equation, but I haven't got a clue with this one. This is an emergency!