Several experiments demonstrate the wave-particle duality of light. Here are a few notable ones:
Double-Slit Experiment: The double-slit experiment is a classic experiment that demonstrates the wave-like behavior of light. In this experiment, a beam of light is passed through a barrier with two closely spaced slits and then observed on a screen behind the barrier. When light passes through the slits, it creates an interference pattern on the screen, indicating that light waves can interfere with each other, much like water waves or sound waves. This interference pattern is a characteristic of waves.
Photoelectric Effect: The photoelectric effect experiment demonstrates the particle-like behavior of light. When light is shone onto a metal surface, it can cause the emission of electrons from the surface. The intensity (brightness) of the light determines the number of emitted electrons, while the frequency (color) of the light determines their energy. This phenomenon cannot be explained by a wave model alone but can be understood by treating light as composed of discrete particles called photons. The photoelectric effect was instrumental in establishing the concept of photons and the particle nature of light.
Compton Scattering: Compton scattering is an experiment that reveals the particle-like behavior of light by showing its interaction with matter as if it were composed of particles. In this experiment, X-rays or high-energy photons are directed at a target material, and the scattered photons are detected. The scattered photons have a different wavelength compared to the incident photons, indicating that they have undergone a change in momentum and energy. This behavior is consistent with the particle-like nature of photons interacting with electrons in the target material.
These experiments, among others, provide evidence for both the wave and particle properties of light, highlighting the wave-particle duality inherent in quantum mechanics.