Albert Einstein's interpretation of the photoelectric effect revolutionized our understanding of light. He proposed that light consists of discreet packets of energy called photons, which carry specific amounts of energy that are proportional to the frequency of the light wave.

Einstein's explanation resolved several key observed phenomena that could not be explained by classical wave theory. For example, according to classical wave theory, increasing the intensity of light should increase the energy of emitted electrons, regardless of the frequency. However, experimental evidence showed that the energy of emitted electrons only depended on the frequency of the incident light, and higher intensities only increased the number of emitted electrons.

To illustrate this concept, let's consider a hypothetical metal surface. When light of a certain frequency, called the threshold frequency, shines onto the metal, electrons can be ejected. If the frequency of light is below the threshold frequency, no electrons are emitted, regardless of the light's intensity. However, if the frequency exceeds the threshold frequency, electrons are ejected, with their kinetic energy depending solely on the frequency of the light.

This observation led Einstein to propose that the energy of a photon is given by the equation E = hf, where E represents the energy, h is Planck's constant, and f is the frequency of the light. The energy of each photon is transferred entirely to a single electron, liberating it from the metal's surface.

Einstein's interpretation of the photoelectric effect laid the groundwork for the development of quantum mechanics, which seeks to explain the behavior of subatomic particles. It demonstrated that light, despite its wave-like nature, also exhibits particle-like properties. This wave-particle duality of light is a fundamental concept in modern physics and has far-reaching implications in various fields, from quantum mechanics to the development of photovoltaic cells.