Answer:
photoelectric effect and the modifications to the Rutherford model is necessary
Step-by-step explanation:
Photoelectric effect refers to emission of electrons when a light of certain frequency falls into a metal surface or a metal atom.
Rutherford, through his alpha particle scattering experiment, proposed the emission of electrons, in which he used a thin gold foil and high energy alpha particle were directed to the foil. He suggested that any light can emit electron from any metal surface.