Xxiii . on the Theory of the Photo - Electric Effect

A discussion is given of the suggestion by Millikan that in the photo-electric effect the energy of the light is transferred to the free electrons of the metal as well as to the bound electrons. anrl the product of the threshold frequency and Planck's constant is interpreted to be equal to the difference between the work nec-essary to remove a ~re'e electron from the metal and the kinetic energy of a free electron within th metal. In cases where the I:Hter is not small compared with the former the theory leads to a lack O'! sharpness in the definition of the threshold. Neglect~ ing variations of kinetic energy, the difference of stoppin, potentials comes out equal to the Peltier coefficient; hence th,e uniformity of stopping potentials for adifferent metals observed by Millikan is due, according to the theory, to the smallness oi • A ClOmplete aceouat of tire work bas appearei in tile Pbylieal Ilniew.