Final answer:
The photoelectric effect is explained by the particle character of EM radiation, specifically through the concept of photons, which are discrete energy packets absorbed by electrons.
Step-by-step explanation:
The photoelectric effect is a direct consequence of the particle character of electromagnetic (EM) radiation. Albert Einstein's analysis of the photoelectric effect revealed that electromagnetic waves must also be quantized into discrete energy packets, known as photons.
The energy of each photon is given by the equation E = hf, where E is the energy, h is Planck's constant and f is the frequency of the EM radiation. This discovery was at odds with the classical wave theory and showed that individual photons of EM radiation are absorbed by individual electrons, with the electron gaining the photon's energy.
The properties of the photoelectric effect cannot be fully explained by the classical wave model of EM radiation, as it fails to explain the observed thresholds for electron emission and the independence of the kinetic energy of the emitted electrons on the intensity of the incoming light. The particle model, however, accurately accounts for these phenomena by invoking the discrete nature of photons which interact with the electrons.