The Photoelectric Effect
Discover how Einstein's 1905 paper on the photoelectric effect laid the foundation for quantum physics.
In 1905, Albert Einstein published a groundbreaking paper on the photoelectric effect, a phenomenon that could not be explained by the prevailing wave theory of light. Einstein suggested that light was composed of discrete energy particles—later termed "quanta"—which directly influenced the emission of electrons from metallic surfaces when exposed to incident light.
According to this theory, the energy of each quantum is proportional to its frequency (E = hf). Einstein's proposal helped to revolutionize physics and laid the groundwork for what we now understand as quantum mechanics. His insights earned him the Nobel Prize in Physics in 1921.
This exhibit explores the science behind Einstein's ideas, the experiments that verified his predictions, and the philosophical implications his work had on the understanding of light and energy.
Einstein's Explanation
Einstein introduced the idea that light energy is quantized—consisting of packets or "quanta" of energy. This theory resolved long-standing questions about why light of certain frequencies could knock electrons out of certain materials but others could not, regardless of the intensity of the light.
The photoelectric effect became one of the most important pieces of evidence for the quantum nature of electromagnetic radiation and formed the cornerstone of modern quantum theory.
A Nobel Legacy
Einstein was awarded the Nobel Prize in Physics in 1921 for his theoretical work on the explanation of the photoelectric effect. While he is often associated more with relativity, the Nobel Committee specifically cited his work in quantum mechanics as the reason for the award.