Wave-particle duality — Science definition
The experimental fact that light (and matter) behaves as both a wave and a stream of particles, depending on how it is observed.
Where it is taught
- Light & the Electromagnetic Spectrum — Waves, Sound & Optics, Physics & Environmental Science, Grade 12
In use
This wave-particle duality is not a contradiction to resolve but a deep truth: which model you use depends on the situation.
Light & the Electromagnetic Spectrum
Questions using wave-particle duality
Problem 1
In your own words, explain what 'wave-particle duality' means for light.
Answer and explanation
Wave-particle duality means light behaves as both a wave and a stream of particles, depending on how you observe it. In experiments like interference and diffraction it acts like a wave, but in the photoelectric effect it acts like discrete particles (photons). Neither model alone is complete — you choose whichever one best describes the situation.