E.2.5 (HL)—Matter wave-particle duality

Hold both descriptions

Quantum objects can show particle-like and wave-like behaviour. The observed property depends on the experiment: photoelectric emission and Compton scattering reveal particle-like transfers, while diffraction reveals wave-like behaviour.

Do not combine classical pictures blindly

Wave-particle duality is not a claim that an object is simultaneously a classical wave and a classical particle. It is a quantum description in which different measurements reveal complementary aspects.

Use scale carefully

For macroscopic objects the de Broglie wavelength is extremely small because momentum is large, so wave effects are not normally detectable. This is a practical limit, not a loss of the relation $\lambda=h/p$.

Common trap

Do not use “wave-particle duality” as an explanation without naming the observation it explains. Match the experiment to the property it demonstrates.