The work function of a photoelectric surface is 3.3 eV. The value of…

The correct answer is Option (1) → \( 8\times10^{14}\,\mathrm{Hz} \)

At the threshold frequency \( \nu_0 \) the photon energy is just equal to the work function, \( h\nu_0 = \phi_0 \).

    \( \phi_0 = 3.3\,\mathrm{eV} = 3.3\times1.6\times10^{-19}\,\mathrm{J} = 5.28\times10^{-19}\,\mathrm{J} \)

    \( \displaystyle \nu_0 = \frac{\phi_0}{h} = \frac{5.28\times10^{-19}\,\mathrm{J}}{6.63\times10^{-34}\,\mathrm{J\,s}} \)

    \( \nu_0 \approx 8\times10^{14}\,\mathrm{Hz} \)

Shortcut: The conversion factor \( e/h \approx 2.42\times10^{14}\,\mathrm{Hz\ per\ eV} \) gives the frequency of a photon directly from its energy in eV: \( 3.3\times2.42\times10^{14} \approx 8\times10^{14}\,\mathrm{Hz} \).

Note: The same question was also asked in CUET (UG) 2026 on 19-05-2026 (Slot 1).

Note: NTA picked this question from an NCERT (2026-27) example and changed the figures. Do not ignore NCERT while practising numericals.

NCERT (2026-27):
Particle Nature of Light: The Photon – …