In 1921, Albert Einstein was awarded the Nobel Prize in Physics for his explanation of the photoelectric effect.

The photoelectric effect is the phenomenon where the emission of electrons from a material is induced by the absorption of photons, particles of light. This discovery was crucial in understanding the wave-particle duality of light and helped pave the way for the development of quantum mechanics.

Einstein's explanation of the photoelectric effect is based on the idea that light consists of discrete packets of energy called photons. These photons transfer their energy to electrons in the material, causing them to be emitted. The energy of each emitted electron depends on the frequency of the absorbed photon.

The photoelectric effect provided substantial evidence for the particle nature of light. Einstein's interpretation not only explained the observed phenomena but also introduced the concept that light energy is quantized.

This recognition of Einstein's work through the Nobel Prize marked a significant milestone in the advancement of our understanding of the quantum nature of light. It confirmed the fundamental nature of light as both a wave and a particle and established the importance of quantum mechanics in explaining the behavior of particles at the atomic and subatomic levels.