1. The problem statement, all variables and given/known data In the photoelectric experiments the photocurrent is proportional to the intensity of the light.Can this result alone be used to distinguish between the classical and quantum theories? 2. Relevant equations 3. The attempt at a solution As I know, this feature of photoelectric effect is the only feture that is compatible with classical concepts.So,this cannot be used like that... [Classical Idea: As you increase the intensity of the light,you are treating the free surface electrons with Electric field and magnetic field of bigger amplitude---Force on them is bigger and they can speed up more promptly giving a bigger value of photoelectric current.] Please check the classical idea.