1. The problem statement, all variables and given/known data When monochromatic light is incident on a metla plate,electrons are emmited only when the frequency of light exceeds a certain frequency. Explain in terms of energy, why this threshold frequency exist and why photon theory of light provides a better explnation of the photorlrctric effect than a wave theory of light. 2. Relevant equations none that i know of 3. The attempt at a solution Its not really a solution but i have talked about energy levels and in atoms and things like that.