Wave-Particle Duality
Toggle wave vs particle view. Builds on Breakdown of Classical Mechanics.
Light hits a metal surface. Classical wave theory predicts that brighter light (more energy) should eject electrons with more kinetic energy. Einstein proposed photons — light as particles with energy E = hf.
To eject electrons with MORE kinetic energy, what should you change?
Higher frequency = more energy per photon! Brightness just means more photons, but each photon's energy depends only on frequency: E = hf. This is the photoelectric effect — the discovery that won Einstein his Nobel Prize.
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Shine light on the metal. Adjust frequency (color) and intensity (brightness). Notice: brighter light ejects MORE electrons, but higher frequency ejects FASTER ones.
λ = h/p
Everything has a wavelength. A baseball's wavelength is 10⁻³⁴ m — too small to ever notice. An electron's is nanometers — measurable!
Photons knock electrons loose in silicon — the photoelectric effect generates electricity
Electrons diffract through crystal lattices, proving de Broglie's wave hypothesis
Electrons drop energy levels and emit photons of specific wavelengths — particle-to-wave conversion
“Is light a wave or a particle? Yes.”
Duality Explorer
Toggle between wave view and particle view for both light and matter. See how the same phenomenon looks completely different depending on how you observe it.
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Calculate the de Broglie wavelength of objects at different speeds. Start with an electron, then try a baseball. Why don't we see quantum effects in everyday life?
Wave-particle duality isn't about light 'choosing' to be one or the other. It's about complementarity: different experiments reveal different aspects of the same underlying reality.