Q.What do you understand by the term wave-particle duality? Where does it apply?

[!TLDR] Wave-particle duality is the principle that light and matter both possess wave-like AND particle-like character simultaneously, with one aspect dominant during interaction (particle) and the other during propagation through comparable-scale structures (wave); it applies to the entire electromagnetic spectrum and, via de Broglie, to all material particle …

Wave-particle duality is the idea that a single physical entity -- whether electromagnetic radiation or a material particle -- cannot be fully described by EITHER a pure wave picture OR a pure particle picture alone; both descriptions are simultaneously necessary, with one or the other dominating depending on the specific situation.\n\nFor ELECTROMAGNETIC RADIATION (section 14.3): phenomena like interference and diffraction are explained only by treating light as a wave, while phenomena like the photoelectric effect, black-body radiation, and Compton scattering are explained only by treating light as a stream of particle-like photons carrying definite energy ($E=h\nu$) and momentum ($p=h/\lambda$). This dual character applies not just to visible light but to the whole electromagnetic spectrum, from radio waves to gamma rays.\n\nFor MATTER (sections 14.5-14.7): de Broglie proposed, and the Davisson-Germer experiment confirmed, that material particles like electrons also possess an associated wavelength $\lambda=h/p$, showing genuine wave-like behaviour (such as diffraction) under the right conditions. As a general rule, PARTICLE nature dominates whenever radiation or matter directly INTERACTS with something (a collision, an …

Explain that wave-particle duality means both wave and particle descriptions are simultaneously valid (for both radiation and matter), citing the specific phenomena that fo …

Describing duality only for light (radiation) and omitting that de Broglie extended the same idea to matter, or describing it as light/matter being 'sometimes a wave, sometimes a particle' rather than the more accurate fram …