Several experiments support the wave and particle nature of light, demonstrating its dual nature known as wave-particle duality. Here are a few key experiments:
Young's Double-Slit Experiment: In the early 1800s, Thomas Young conducted an experiment that showed the wave-like behavior of light. He shone a beam of light through a barrier with two narrow slits, and on the other side, he observed an interference pattern of light and dark fringes. This result indicated that light waves interfere with each other, similar to water waves or sound waves. The experiment demonstrated the wave nature of light.
Photoelectric Effect: The photoelectric effect, studied extensively by Albert Einstein and others, provided evidence for the particle-like nature of light. When light shines on a metal surface, it can eject electrons from the surface. The energy of the ejected electrons depends on the frequency of the incident light, not its intensity. This experiment showed that light behaves as discrete particles, called photons, with each photon carrying a specific amount of energy. The photoelectric effect won Einstein the Nobel Prize in Physics in 1921.
Compton Scattering: In the early 20th century, Arthur Compton performed experiments involving X-rays and electrons, which demonstrated the particle nature of light. When X-rays were directed at a target, they scattered off the electrons in the target material. The scattered X-rays exhibited a change in wavelength, indicating that they were interacting with the electrons as if they were particles. This phenomenon, known as Compton scattering, provided evidence for the particle-like behavior of light.
Davisson-Germer Experiment: In 1927, Clinton Davisson and Lester Germer conducted an experiment that confirmed the wave-like behavior of electrons, which can be considered as particles of matter. They directed a beam of electrons at a nickel crystal and observed an interference pattern similar to Young's double-slit experiment with light. This result demonstrated the wave-particle duality not only for light but also for matter particles.
These experiments, among others, collectively support the wave-particle duality of light, showing that light can exhibit both wave-like and particle-like properties depending on the experimental setup and observations.