The wave theory of light can not explain the phenomenon of
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Photoelectric effect
The wave theory (Huygens' principle) explains refraction, reflection and dispersion. It fails for the photoelectric effect, which needs light to act as photons.
The wave theory cannot explain the existence of a threshold frequency, the instantaneous emission, or the independence of the maximum kinetic energy from intensity.
Note: A similar question was also asked in CUET (UG) 2026 on 19-05-2026 (Slot 1), and in CUET (UG) 2023 on 07-06-2023 (Slot 3).
NCERT (2026-27):
Photoelectric Effect and Wave Theory of Light – “… This conclusion is again in striking contrast to observation (iv) that the photoelectric emission is instantaneous. In short, the wave picture is unable to explain the most basic features of photoelectric emission.”