22.1.1—Electromagnetic radiation has a particulate nature

Electromagnetic radiation shows wave behaviour such as interference and diffraction and particle behaviour such as quantised photon interactions.

Use the model that explains the observation; neither classical wave nor classical particle language alone covers every experiment.

A diffraction pattern supports wave behaviour, while the photoelectric effect requires discrete energy transfers.

Wave–particle duality is not a claim that light alternates between two physical substances during travel.