Which one among the following shows particle nature of light?

The correct answer is Option (3) → Photoelectric effect

The particle nature of light means that light carries energy in separate packets, photons, each of energy \( h\nu \).

In the photoelectric effect light ejects electrons from a metal surface. Emission starts at once, needs a minimum (threshold) frequency, and the maximum kinetic energy of the electrons depends on the frequency, not on the intensity. The wave picture cannot explain these facts; Einstein explained them by treating light as photons, each giving its whole energy to one electron:

    \( \displaystyle K_{\mathrm{max}} = h\nu - \phi_0 \)

Note: A similar question was also asked in CUET (UG) 2023 on 26-05-2023 (Slot 1) and on 25-05-2023 (Slot 3).

NCERT (2026-27):
Wave Nature of Matter – “The dual (wave-particle) nature of light (electromagnetic radiation, in general) comes out clearly from what we have learnt in this and the preceding chapters. The wave nature of light shows up in the phenomena of interference, diffraction and polarisation. On the other hand, in the photoelectric effect and Compton effect which involve energy and momentum transfer, radiation behaves as if it is made up of a bunch of particles – the photons.”