The energy of a photon of wavelength λ is

The correct answer is Option (2) → \( \displaystyle\frac{hc}{\lambda} \)

In the photon picture the energy of a photon is proportional to its frequency, \( E = h\nu \), and the frequency and wavelength of light are related by \( c = \nu\lambda \).

    \( \displaystyle E = h\nu = \frac{hc}{\lambda} \)

Shortcut: Check the units: \( hc \) has the unit \( \mathrm{J\,m} \), so only \( hc/\lambda \) gives joule. Option (1) gives \( \mathrm{J\,m^{2}} \), Option (3) gives \( \mathrm{J\,s^{2}} \) and Option (4) gives \( \mathrm{J^{-1}} \).

NCERT (2026-27):
Particle Nature of Light: The Photon – “… (iii) All photons of light of a particular frequency ν, or wavelength λ, have the same energy E (=hν = hc/λ) and momentum p (= hν/c = h/λ), whatever the intensity of radiation may be.”