1. Young's Double Slit Experiment:
* Setup: Shine the beam of light (or other particles) through two closely spaced slits. Observe the pattern on a screen behind the slits.
* Wave behavior: If the beam is behaving as a wave, the waves passing through each slit will interfere, creating an interference pattern of alternating bright and dark bands on the screen.
* Particle behavior: If the beam is behaving as a stream of particles, you'd expect to see two bright bands behind each slit, corresponding to where the particles hit the screen.
2. Diffraction:
* Setup: Shine the beam through a small opening or past an obstacle. Observe the pattern on a screen behind the object.
* Wave behavior: Waves will bend around obstacles, resulting in a diffraction pattern that spreads out the beam.
* Particle behavior: Particles should travel in straight lines and not bend around the object.
3. Photoelectric Effect:
* Setup: Shine the beam onto a metal surface and measure the kinetic energy of the emitted electrons.
* Wave behavior: Classical physics predicts that the energy of the emitted electrons should depend on the intensity of the light.
* Particle behavior: Einstein's explanation of the photoelectric effect states that light behaves as particles called photons. The energy of a photon is proportional to its frequency, and this energy is transferred to the electrons, causing them to be emitted. This explains why the kinetic energy of the emitted electrons depends on the frequency of the light, not its intensity.
4. Compton Scattering:
* Setup: Shine the beam onto a material and measure the change in the wavelength of the scattered photons.
* Wave behavior: Classical physics predicts that the wavelength of scattered light should not change.
* Particle behavior: The Compton effect demonstrates that photons can collide with electrons like particles, causing them to lose energy and change direction. This results in a change in the wavelength of the scattered photons, which can be measured.
Important Note: The wave-particle duality is a fundamental concept in quantum mechanics. It means that light and other particles exhibit both wave-like and particle-like behavior, depending on how they are observed. These experiments are not designed to prove that light is *either* a wave or a particle; they demonstrate the duality of its nature.
