Einstein’s photoelectric equation depicts which nature of light?

The correct answer is Option (2) → Particle

Option (1) Wave — Incorrect. In the wave picture, the electrons absorb energy continuously. Then the maximum kinetic energy should grow with intensity, and there should be no threshold frequency. The photoelectric observations show neither of these.

Option (2) Particle — Correct. Einstein’s equation \( K_{\mathrm{max}}=h\nu-\phi_0 \) treats light as quanta (photons), each of energy \( h\nu \), with one photon absorbed by one electron. This is the particle (photon) description of light.

NCERT (2026-27):
Particle Nature of Light: the Photon – “Photoelectric effect thus gave evidence to the strange fact that light in interaction with matter behaved as if it was made of quanta or packets of energy, each of energy hν. … (i) In interaction of radiation with matter, radiation behaves as if it is made up of particles called photons.”