Which phenomenon shows the particle nature of light?

The photoelectric effect illustrates light's particle nature. When light, composed of photons, strikes a material surface, it can eject electrons. This phenomenon cannot be explained solely by light's wave-like properties but requires the concept of photons, which carry discrete amounts of energy and momentum. Each photon's energy is proportional to its frequency (E = hf). If a photon's energy exceeds the material's work function, it can liberate an electron. Albert Einstein's explanation of the photoelectric effect in 1905 provided compelling evidence for the particle nature of light and earned him the Nobel Prize in Physics in 1921.